单选题Radiation can spread a fire by （）.Atransmitting the heat of a fire through the ship s metalBburning liquids flowing into another spaceCheated gases flowing through ventilation systemsDthe transfer of heat across an unobstructed space
单选题
Radiation can spread a fire by （）.
A
transmitting the heat of a fire through the ship s metal
B
burning liquids flowing into another space
C
heated gases flowing through ventilation systems
D
the transfer of heat across an unobstructed space
参考解析
解析：
暂无解析
相关考题：
发生火情时，客人们能用电梯吗?A.Can guests use the stairs when a fire appears?B.Can guests use the elevators when a fire presents?C.Can guests use the lifts when a fire occurs?D.Can guests use the ladders when a fire breaks up?
共用题干Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.The underlined word"significant"in Paragraph 3 most probably means______.A:fatal B:meaningfulC:remarkableD:harmful
共用题干第三篇 Nuclear Power and Its DangerNqclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital or-gans.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.if the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones. But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce them-selves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done with-out the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine, then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can cause serious consequences even at the lowest level_________.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干第三篇 Nuclear Power and Its DangerNqclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital or-gans.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.if the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones. But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce them-selves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done with-out the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine, then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Which of the following can be best inferred from the passage?A:The importance of protection from radiation cannot be over-emphasized.B:The mystery about radiation remains unsolved.C:Cancer is mnainly caused by radiation.D:Radiation can hurt those who are not aware of its danger.
共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can________.A:kill large numbers of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.According to the passage,the danger of nuclear power lies in________.A:nuclear mysteryB:radiation detectionC:nuclear radiationD:radiation level
共用题干第一篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.It can't be seen or heard,or touched or tasted,even though it may be all around us.There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.The word"significant"in Paragraph 3 most probably means________. A:fatalB:meaningfulC:remarkableD:harmful
共用题干Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.According to the passage,the danger of nuclear power lies in______.A:nuclear mysiery B:radiation detectionC:nuclear radiation D:radiation level
共用题干Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.Nuclear radiation has a certain mystery about it,partly because it cannot be detected by human senses.lt can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver.Similarly,we can't sense radioactivity without a radiation detector.But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant．This is the case when only a few cells are hit,and if they are killed outnght.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.They can grow into cancer.Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation1 can cause serious consequences even at the lowest level______.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干第三篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radia-tion.Nuclear radiation has a certain mystery about it,partly because it canhot be detected by human senses. It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be donewithout the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.According to the passage,the danger of nuclear power lies in___________.A:nuclear mysteryB:radiation detectionC:nuclear radiationD:radiation level
共用题干第三篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radia-tion.Nuclear radiation has a certain mystery about it,partly because it canhot be detected by human senses. It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be donewithout the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can cause serious consequences even at the lowest level___________.A:when it kills few cellsB:if it damages few cellsC:though the damaged cells can repair themselvesD:unless the damaged cells can reproduce themselves
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can_______.A:kill large number of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干第三篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radia-tion.Nuclear radiation has a certain mystery about it,partly because it canhot be detected by human senses. It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be donewithout the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Radiation can hurt us in the way that it can__________.A:kill large numbers of cells in main organs so as to cause death immediatelyB:damage cells which may grow into cancer years laterC:affect the healthy growth of our offspringD:all of the above
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth.Radiation can cause serious consequences even at the lowest level_______.A:when it kills a few cellsB:if it damages a few cellsC:though the damaged cells can repair themselvesD:if the damaged cells reproduce themselves
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth.According to the passage,the danger of nuclear power lies in_______.A:nuclear mystery B:radiation detectionC:nuclear radiation D:radiation level
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth. Which of the following can be best inferred from the passage?A:The importance of protection from radiation cannot be over-emphasized.B:The mystery about radiation remains unsolved.C:Cancer is mainly caused by radiation.D:Radiation can hurt those who are not aware of its danger.
共用题干第三篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radia-tion.Nuclear radiation has a certain mystery about it,partly because it canhot be detected by human senses. It can't be seen or heard,or touched,or tasted,even though it may be all around us.There are other things like that.For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beings and other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright.Your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be donewithout the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result.Or a child can be born weak or liable to serious illness as result of radiation absorbed by its grandparents.Radiation can hurt us.We must know the truth.Which of the following can be best inferred from the passage?A:The importance of protection from radiation cannot be over-emphasized.B:The mystery about radiation remains unsolved.C:Cancer is mainly caused by radiation.D:Radiation can hurt those who are not aware of its danger.
共用题干第二篇Nuclear Power and Its DangerNuclear power's danger to health,safety,and even life itself can be summed up in one word:radiation.There is a certain mystery about nuclear radiation,partly because it cannot be detected by human senses. It can't be seen or heard,or touched or tasted,even though it may be all around us. There are other things like that. For example,radio waves are all around us but we can't detect them,sense them,without a radio receiver. Similarly,we can't sense radioactivity without a radiation detector. But unlike common radio waves,nuclear radiation is not harmless to human beingsand other living things.At very high levels,radiation can kill an animal or human being outright by killing masses of cells in vital organs.But even the lowest level of radiation can do serious damage.There is no level of radiation that is completely safe.If the radiation does not hit anything important,the damage may not be significant. This is the case when only a few cells are hit,and if they are killed outright,your body will replace the dead cells with healthy ones.But if the few cells are only damaged,and if they reproduce themselves,you may be in trouble.They reproduce themselves in a deformed way.Theycan grow into cancer. Sometimes this does not show up for many years.This is another reason for some of the mystery about nuclear radiation.Serious damage can be done without the victim being aware at the time that damage has occurred.A person can be irradiated and feel fine,then die of cancer five,ten,or twenty years later as a result. Or a child can be born weak or liable to serious illness as result of radiation absorbed by his grandparents.Radiation can hurt us.We must know the truth.The word"significant"in Paragraph 3 most probably means_______.A:fatal B:meaningfulC:remarkable D:harmful
单选题In the event of a fire, the doors to a stair tower must be closed to prevent the spread of fire by （）.AconvectionBconductionCradiationDventilation
单选题Fire may be spread by which means?（）AConduction of heat to adjacent surfacesBDirect radiationCConvectionDAll of the above
单选题What is meant by the term overhaul in firefighting?（）ASlow down the spread of fire by cooling adjacent structuresBCover the fire with foamCSmother the fire with a blanket or similar objectDBreak up solid objects to ensure that any deep seated fires are extinguished
单选题Ventilation systems connected to a compartment in which a fire is burning are normally closed to prevent the rapid spread of the fire by（）.AconvectionBconductionCradiationDspontaneous combustion
单选题The blocking or absence of fire dampers can cause（）.Athe accumulation of explosive gasesBfaster cooling of the fireCthe fire to spread through the ventilation systemDfixed foam systems to be ineffective
单选题Fire dampers prevent the spread of fire by（）.AconvectionBconductionCradiationDdirect contact
单选题The primary function(s) of an automatic sprinkler system is(are) to（）.Aextinguish the fire which triggers itBlimit the spread of fire and control the amount of heat producedCprotect people in the areas which have sprinkler headsDalert the crew to the fire
单选题Blocking open or removing fire dampers can cause（）.Afixed foam systems to be ineffectiveBfaster cooling of the fireCthe accumulation of explosive gasesDthe fire to spread through the ventilation system
单选题Radiation spreads a fire by（）.Atransferring heat across an unobstructed spaceBheated gases flowing through ventilation systemsCburning liquids flowing into another spaceDtransmitting the heat of a fire through the ship's metal