问答题Most people would describe water like a colorless liquid. They (1) _______would know that in very cold conditions it becomes a solid calledice and that when heating on a fire it becomes a vapor called steam. (2) _______However, water, they would say, is a liquid. We have learned thatwater consists of molecules composed with two atoms of hydrogen (3) _______and one atom of oxygen, which we describe by the formula H2O.This is equally true of the solid called ice and the gas called steam.Chemically there is no difference between the gas, the liquid, andthe solid, all of which is made up of molecules with the formula H2O. (4) _______This is true of other chemical substances; most of them can exist asgases or as liquids or as solids. We may normally think of iron as asolid, but if we will heat it in a furnace, it will melt and become a (5) _______liquid, and at very high temperatures it will become a gas. Nothingvery permanent occurs when a gas changes into a liquid or a solid.Everyone knows that ice, which has been made by freezing water,can be melted again by warmed and that steam can be condensed (6) _______on a cold surface to become liquid water. In fact, it is only becausewater is so a familiar substance that different names are used for (7) _______the solid, liquid and gas. Most substances are only familiar with (8) _______us in one state, because the temperatures requiring to turn them (9) _______into gases are very high, or the temperatures necessary to turn theminto solids are so low. Water is an exception in this respect, whichis another reason why its three states have given three different (10) _______names.
问答题
Most people would describe water like a colorless liquid. They (1) _______would know that in very cold conditions it becomes a solid calledice and that when heating on a fire it becomes a vapor called steam. (2) _______However, water, they would say, is a liquid. We have learned thatwater consists of molecules composed with two atoms of hydrogen (3) _______and one atom of oxygen, which we describe by the formula H2O.This is equally true of the solid called ice and the gas called steam.Chemically there is no difference between the gas, the liquid, andthe solid, all of which is made up of molecules with the formula H2O. (4) _______This is true of other chemical substances; most of them can exist asgases or as liquids or as solids. We may normally think of iron as asolid, but if we will heat it in a furnace, it will melt and become a (5) _______liquid, and at very high temperatures it will become a gas. Nothingvery permanent occurs when a gas changes into a liquid or a solid.Everyone knows that ice, which has been made by freezing water,can be melted again by warmed and that steam can be condensed (6) _______on a cold surface to become liquid water. In fact, it is only becausewater is so a familiar substance that different names are used for (7) _______the solid, liquid and gas. Most substances are only familiar with (8) _______us in one state, because the temperatures requiring to turn them (9) _______into gases are very high, or the temperatures necessary to turn theminto solids are so low. Water is an exception in this respect, whichis another reason why its three states have given three different (10) _______names.
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Water is the __46___ of all the things we eat and drink . Not many people understand this but __47____ quite true . The human body can go without ___48___ for a long time . We’ve got many examples for this . Yet two __49___ three days without water can usually make people __50____ . Man can’t live __51____ water .Many people don’t understand how ___52__ water the human body needs __53___ work well , and many people , especially young people , do not drink enough , ___54__ in very hot weather . Our body has mostly water , about 65% to 75% . That is to say about two thirds of our body is water . When we do sports , some of the water will get away from our body . __55 _ we don’t drink some water , we won’t have enough water． And if we don’t have enough water , we’ll feel tired and many of us will get ill . So you know how important water is to us .46.___________( )46. A. importantB. most importantC. more importantD. different
The sea looks very pretty when the sun is shining on it. It can be very rough when there is a strong wind. The sea is very big. It covers three quarters of the globe! The sea is also very deep in some places. There is one spot near the Philippines , where the sea is about 11 kilometers deep. The highest mountain in the world is about 9 kilometers high. If that mountain was put in the sea at that place, there would still be 3 kilometers of water above it! What a deep place! In most parts of the sea, there are plenty of fishes and plants. Some live near the top of the sea. Others live deep down. There are millions of tiny living things that float in the sea. Many fish live by eating them. The sea can be very cold. When the diver goes downwards, the sea becomes colder and colder. When the diver goes deeper, the water exerts greater pressure.1、There is one spot near the Philippines, where the sea is as deep as ( ).A、13 kilometersB、 9 kilometersC、 2 kilometersD、 11 kilometers2、There are millions of tiny living things that float in the sea, and( ).A、they live by eating fishB、they live by eating plantsC、they are good food for many fishD、they live by eating worms3、Which of the following statements is true? ( )A、When the diver dives under the sea, he gets colder and colder.B、When the diver sinks to the bottom, he is to be colder and colder.C、When the diver sinks in the sea, he will be rather cold.D、When the diver dives downward, the sea gets colder and colder.4、From the information given, why has the diver to wear a diving suit? ( )A、Because the diver is likely to be attacked by fish.B、 Because the water at great depths is very cold.C、 Because the salt water seems unsuitable for diver.D、 Because the pressure of water at great depths is immense ( 巨大的 ).
Once a week my aunt would announce, "I am going to have my bath today."Now most people find it fairly simple to have a bath.You probably remember how it goes.You enter the bathroom, you put the plug in, turn on the hot water, get into the bath, wash, sing, get out, dry yourself and exit.My aunt's approach was more epic(宏大的), like one of those long Eisenstein films where people seem to be climbing up the same flight of stairs forever.My aunt would first slowly collect her clean linen(亚麻布衬衫), so as to have it all ready for changing into after her bath.This involved sorting out her linen, which took up most of the morning.Sometimes she would find an old letter buried among her linen, become interested in the memories it aroused and have to postpone the bath until the next day.But if all went well, she would have a bite of lunch and start Phase Two around two o'clock.Phase Two was washing out the bath.She would wash the bath very thoroughly, rinse(冲洗) it with running cold water, rewash it and then carefully feel the whole surface with her fingers.If there was the slightest blemish, she would clean the whole bath out again.This took about an hour.Then she would fill the bath.By this time she was feeling a bit hungry and exhausted.So she would put on the kettle for a cup of tea.Several cups of tea and several cream crackers (her favourite food) later, she would go back to the bathroom.And find the water stone cold.1.According to the writer, most people().A.read magazines in the bathB.make bath time a special occasionC.sing when they are in the bathD.have a bath once every other week2.The writer's aunt().A.never got used to taking a bath regularlyB.always treated bathtime as an eventC.hated climbing the stairs to the bathroomD.would collect her new linen quickly3.How did she use to spend most of the morning?()A.Reading old letters.B.Preparing lunch.C.Getting the bath water hot.D.Sorting out her linen.4.Why might the writer's aunt put off bathing until the next day?()A.She might get fascinated by an old letter.B.She would sometimes get too tired.C.She would sometimes have lunch instead.D.She might start ironing the linen.5.She would never fill the bath until she().A.had cleaned it at least three timesB.had had several cups of teaC.had polished it inside and outsideD.had made sure it was perfectly clean
When water( ), it will be changed into vapour.A. is heatedB. was heatedC. will be heatedD. would heated
When sailing ill cold zones,_______should be drained of water.A.the ventilation pipeB.the water line for fire fighting on the deckC.the fuel oil lineD.the water supplying line in bath room
The dew point is reached when the ______.A.temperature of the air equals the temperature of the seawaterB.atmospheric pressure is 14.7 lbs. per square inchC.relative humidity reaches 50%D.air becomes saturated with water vapor
A foam-type portable fire extinguisher would be most useful in combating a fire in ______.A.solid materials such as wood or bales of fiberB.flammable liquidsC.a piece of electrical equipmentD.combustible metallic solid
共用题干Where Did the Earth's Water Come From?Earth is located within the"snow line"of the solar system,the region closest to the Sun where H2 0 is primarily in liquid or gaseous form,if at all.______(46)The snow line phenomena is reflected in the water content of planets like Mercury,Venus,and Mars. Water is absent on Mercury.On Venus,H2O only exists as a trace element in the atmosphere.Mars only has a thin veneer of ice in its polar regions.In general,water is rare within the snow line.Why does Earth have so much water relative to the other inner planets?71%of the surface is covered in the oceans,more than half of which is deeper than 3,000 meters,with an approximate total volume of 1.3 billion cu km.______(47)There are various theories as to where all the Earth's water came from,but several theories have fared better than the others.______(48)When the Earth was in the process of forming,with a radius just 40%smaller than at present,it would have had enough gravity to hold on to a tenuous atmosphere with water vapor. The first water vapor on the planet would have come from the planet's internals,where volatile(low weight)chemicals would have a tendency to float to the top,and heavy chemicals(iron and nickel)would sink.Though the first of Earth's water came about through volcanism,this alone probably didn't produce enough to form stable pools on the surface.______(49)Comparing the isotope ratios of water on Earth and water from comets and asteroids has revealed that the majority of the Earth's water comes from asteroids.Throughout its history,Earth's water has increased in volume due to biological processes. In the early seas of Earth,hydrogen sulfide would have been in great supply,which,when reacted with carbon dioxide from the atmosphere during photosynthesis in sulfide-reducing bacteria,would have produced hydrogen,sulfur,and water.______(50)________（49）A: More water was added to the planet during several hypothesized large impacts from asteroids from the outer asteroid belt.B:We know that the oceans existed as early as 100 million years after the formation of the Earth.C:Still,the oceans only make up 0.023%of the Earth's total mass.D:Astronomers say Earth s water may have come from space.E:The snow line is located in the outerasteroid belt,between the orbits of Mars and Jupiter. F: Many geologists believe that the majority of Earth's water generated through this process.
共用题干The SeaWhat do you know about the sea?We know that it looks very pretty when the sun is shining on it.We also know that it can be very rough when there is a strong wind.What other things do we know about it?The first thing to remember is that the sea is very big.When you look at the map of the world you will find there is more water than land.The sea covers three quarters of the world.The sea is also very deep in some places.It is not deep everywhere.Some parts of the sea are very shal-low.But in some places the depth of the sea is very great.There is one spot,near Japan,where the sea is nearly 11 kilometers deep!The highest mountain in the world is about 9 kilometers high.If that mountainwere put into the sea at that place,there would be 2 kilometers of water above it！What a deep place!If you have swum in the sea,you know that it is salty.You can taste the salt,Rivers,which fi0w into the sea.carry salt from the land into the sea.Some parts of the sea are saltier than other parts,There i、one sea,called the Dead Sea,which is very salty.It is so salty that swimmers cannot sink!Fish cannot live in theDead Sea!In most parts of the sea,there are plenty of fishes and plants.Some live near the top of the sca.Othurslive deep down.There are millions of tiny living things that float in the sea.These floating things are so smallthat it is hard to see them.Many fish live by eating them.The sea can be very cold.Divers,who go deep down in the sea,know this.On the top the water may bewarm.When the diver goes downwards,the sea becomnes colder and colder. Another thing happens.When the diver goes deeper,the water above presses down on him.It squeezes him.Then the diver has to wear clothesmade of metal.But he cannot go very deep.Some people who wanted to go very deep used a very strong diving ship!They went down to the deepest part of the sea in it.They went down to a depth of eleven kilometers!The sea is 6 kilometers in depth on average.A:RightB:WrongC:Not mentioned
共用题干The SeaWhat do you know about the sea?We know that it looks very pretty when the sun is shining on it.We also know that it can be very rough when there is a strong wind.What other things do we know about it?The first thing to remember is that the sea is very big.When you look at the map of the world you will find there is more water than land.The sea covers three quarters of the world.The sea is also very deep in some places.It is not deep everywhere.Some parts of the sea are very shal-low.But in some places the depth of the sea is very great.There is one spot,near Japan,where the sea is nearly 11 kilometers deep!The highest mountain in the world is about 9 kilometers high.If that mountainwere put into the sea at that place,there would be 2 kilometers of water above it！What a deep place!If you have swum in the sea,you know that it is salty.You can taste the salt,Rivers,which fi0w into the sea.carry salt from the land into the sea.Some parts of the sea are saltier than other parts,There i、one sea,called the Dead Sea,which is very salty.It is so salty that swimmers cannot sink!Fish cannot live in theDead Sea!In most parts of the sea,there are plenty of fishes and plants.Some live near the top of the sca.Othurslive deep down.There are millions of tiny living things that float in the sea.These floating things are so smallthat it is hard to see them.Many fish live by eating them.The sea can be very cold.Divers,who go deep down in the sea,know this.On the top the water may bewarm.When the diver goes downwards,the sea becomnes colder and colder. Another thing happens.When the diver goes deeper,the water above presses down on him.It squeezes him.Then the diver has to wear clothesmade of metal.But he cannot go very deep.Some people who wanted to go very deep used a very strong diving ship!They went down to the deepest part of the sea in it.They went down to a depth of eleven kilometers!The sea looks beautiful when it is calmn.A:RightB:WrongC:Not mentioned
共用题干The SeaWhat do you know about the sea?We know that it looks very pretty when the sun is shining on it.We also know that it can be very rough when there is a strong wind.What other things do we know about it?The first thing to remember is that the sea is very big.When you look at the map of the world you will find there is more water than land.The sea covers three quarters of the world.The sea is also very deep in some places.It is not deep everywhere.Some parts of the sea are very shal-low.But in some places the depth of the sea is very great.There is one spot,near Japan,where the sea is nearly 11 kilometers deep!The highest mountain in the world is about 9 kilometers high.If that mountainwere put into the sea at that place,there would be 2 kilometers of water above it！What a deep place!If you have swum in the sea,you know that it is salty.You can taste the salt,Rivers,which fi0w into the sea.carry salt from the land into the sea.Some parts of the sea are saltier than other parts,There i、one sea,called the Dead Sea,which is very salty.It is so salty that swimmers cannot sink!Fish cannot live in theDead Sea!In most parts of the sea,there are plenty of fishes and plants.Some live near the top of the sca.Othurslive deep down.There are millions of tiny living things that float in the sea.These floating things are so smallthat it is hard to see them.Many fish live by eating them.The sea can be very cold.Divers,who go deep down in the sea,know this.On the top the water may bewarm.When the diver goes downwards,the sea becomnes colder and colder. Another thing happens.When the diver goes deeper,the water above presses down on him.It squeezes him.Then the diver has to wear clothesmade of metal.But he cannot go very deep.Some people who wanted to go very deep used a very strong diving ship!They went down to the deepest part of the sea in it.They went down to a depth of eleven kilometers!Divers have to use a very strong diving ship when they want to go down to the deepest part of the seamainly because it is extremely cold there.A:RightB:WrongC:Not mentioned
共用题干The SeaWhat do you know about the sea?We know that it looks very pretty when the sun is shining on it.We also know that it can be very rough when there is a strong wind.What other things do we know about it?The first thing to remember is that the sea is very big.When you look at the map of the world you will find there is more water than land.The sea covers three quarters of the world.The sea is also very deep in some places.It is not deep everywhere.Some parts of the sea are very shal-low.But in some places the depth of the sea is very great.There is one spot,near Japan,where the sea is nearly 11 kilometers deep!The highest mountain in the world is about 9 kilometers high.If that mountainwere put into the sea at that place,there would be 2 kilometers of water above it！What a deep place!If you have swum in the sea,you know that it is salty.You can taste the salt,Rivers,which fi0w into the sea.carry salt from the land into the sea.Some parts of the sea are saltier than other parts,There i、one sea,called the Dead Sea,which is very salty.It is so salty that swimmers cannot sink!Fish cannot live in theDead Sea!In most parts of the sea,there are plenty of fishes and plants.Some live near the top of the sca.Othurslive deep down.There are millions of tiny living things that float in the sea.These floating things are so smallthat it is hard to see them.Many fish live by eating them.The sea can be very cold.Divers,who go deep down in the sea,know this.On the top the water may bewarm.When the diver goes downwards,the sea becomnes colder and colder. Another thing happens.When the diver goes deeper,the water above presses down on him.It squeezes him.Then the diver has to wear clothesmade of metal.But he cannot go very deep.Some people who wanted to go very deep used a very strong diving ship!They went down to the deepest part of the sea in it.They went down to a depth of eleven kilometers!The deeper a diver goes down in the sea,the greater water pressure he bears?A:RightB: WrongC:Not mentioned
When did you last see a polar bear?On a trip to a zoo,perhaps?If you had attended a winter activity in New York a few years ago,you would have seen a whole polar bear club.These"Polar Bears"are people who-meet frequently in winter to swim in freezing cold water.That day,the air temperature was 3oC,and the water temperature was a bit higher.The members of the Polar Bear Club at Coney Island,New York are usually about the age of 60.Members must satisfy two requirements.First,they must get along well with everyone else in the group.This is very important because there are so many different kinds of people in the club.Polar Bears must also agree to swim outdoors at least twice a month from November through February.Doctors do not agree about the medical effects of cold-water swimming.Some are worried about the dangers of a condition in which the body′s temperature drops so low that finally the heart stops.Other doctors,however,point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.The Polar Bears themselves are satisfied with the benefits（or advantages）of cold-water swimming.They say that their favorite form of exercise is very good for the circulatory system（循环系统）because it forces the blood to move fast to keep the body warm.Cold-water swimmers usually turn bright red after a few minutes in the water.A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.The main benefits（or advantages）of cold-water swimming are probably mental.The Polar Bears love to swim year-round;they find it fun and relaxing.As one 70-year-old woman says,"When I go into the water,I pour my troubles into the ocean and let them float away."The passage is mainly aboutA.a group of cold-water-swimming loversB.the Polar Bears'life in New YorkC.doctors'ideas about cold-water swimmingD.the requirements of the Polar Bear Club
When did you last see a polar bear?On a trip to a zoo,perhaps?If you had attended a winter activity in New York a few years ago,you would have seen a whole polar bear club.These"Polar Bears"are people who-meet frequently in winter to swim in freezing cold water.That day,the air temperature was 3oC,and the water temperature was a bit higher.The members of the Polar Bear Club at Coney Island,New York are usually about the age of 60.Members must satisfy two requirements.First,they must get along well with everyone else in the group.This is very important because there are so many different kinds of people in the club.Polar Bears must also agree to swim outdoors at least twice a month from November through February.Doctors do not agree about the medical effects of cold-water swimming.Some are worried about the dangers of a condition in which the body′s temperature drops so low that finally the heart stops.Other doctors,however,point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.The Polar Bears themselves are satisfied with the benefits（or advantages）of cold-water swimming.They say that their favorite form of exercise is very good for the circulatory system（循环系统）because it forces the blood to move fast to keep the body warm.Cold-water swimmers usually turn bright red after a few minutes in the water.A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.The main benefits（or advantages）of cold-water swimming are probably mental.The Polar Bears love to swim year-round;they find it fun and relaxing.As one 70-year-old woman says,"When I go into the water,I pour my troubles into the ocean and let them float away."The Polar Bears like to swim all the year round,forA.they can remain youngB.it is an easy way to keep the body warm in winterC.they find it enjoyable and interestingD.they might meet fewer troubles in life
When did you last see a polar bear?On a trip to a zoo,perhaps?If you had attended a winter activity in New York a few years ago,you would have seen a whole polar bear club.These"Polar Bears"are people who-meet frequently in winter to swim in freezing cold water.That day,the air temperature was 3oC,and the water temperature was a bit higher.The members of the Polar Bear Club at Coney Island,New York are usually about the age of 60.Members must satisfy two requirements.First,they must get along well with everyone else in the group.This is very important because there are so many different kinds of people in the club.Polar Bears must also agree to swim outdoors at least twice a month from November through February.Doctors do not agree about the medical effects of cold-water swimming.Some are worried about the dangers of a condition in which the body′s temperature drops so low that finally the heart stops.Other doctors,however,point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.The Polar Bears themselves are satisfied with the benefits（or advantages）of cold-water swimming.They say that their favorite form of exercise is very good for the circulatory system（循环系统）because it forces the blood to move fast to keep the body warm.Cold-water swimmers usually turn bright red after a few minutes in the water.A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.The main benefits（or advantages）of cold-water swimming are probably mental.The Polar Bears love to swim year-round;they find it fun and relaxing.As one 70-year-old woman says,"When I go into the water,I pour my troubles into the ocean and let them float away."DoctorsA.encourage people to take part in cold-water swimming activelyB.point out the possible danger of blood illness during cold-water swimmingC.believe swimming is helpful both in winter and in summerD.have different ideas about the medical effects of cold-water swimming
When did you last see a polar bear?On a trip to a zoo,perhaps?If you had attended a winter activity in New York a few years ago,you would have seen a whole polar bear club.These"Polar Bears"are people who-meet frequently in winter to swim in freezing cold water.That day,the air temperature was 3oC,and the water temperature was a bit higher.The members of the Polar Bear Club at Coney Island,New York are usually about the age of 60.Members must satisfy two requirements.First,they must get along well with everyone else in the group.This is very important because there are so many different kinds of people in the club.Polar Bears must also agree to swim outdoors at least twice a month from November through February.Doctors do not agree about the medical effects of cold-water swimming.Some are worried about the dangers of a condition in which the body′s temperature drops so low that finally the heart stops.Other doctors,however,point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.The Polar Bears themselves are satisfied with the benefits（or advantages）of cold-water swimming.They say that their favorite form of exercise is very good for the circulatory system（循环系统）because it forces the blood to move fast to keep the body warm.Cold-water swimmers usually turn bright red after a few minutes in the water.A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.The main benefits（or advantages）of cold-water swimming are probably mental.The Polar Bears love to swim year-round;they find it fun and relaxing.As one 70-year-old woman says,"When I go into the water,I pour my troubles into the ocean and let them float away."According to the passage,some doctors believe it is true thatA.you are healthy if cold-water swimming turns your skin color blueB.cold-water swimming causes more heart attacks in summer than in winterC.cold-water swimming can make the body temperature dangerously highD.Polar Bears are bears swimming in freezing water
–Would you like something to drink ？ -（）, please.ATwo cups of watersBTwo cup of watersCTwo cups of water
单选题A class "B" fire would most likely occur in the （）.Amain switchboardBengine room bilgeCbreathing compartmentDelectric fresh water transfer pump
单选题The steam boiler is part of a closed loop steam, whereby, after the energy of the steam is used up and it becomes water again, （） is collected and returned back to the boiler for heating up again to steam.Athe formerBthe firstCthe latterDthe last
单选题A definite advantage of using water as a fire extiguishing agent is its characteristic of（）.Aalternate expansion and contraction as water in a liquid state becomes a vaporBabsorption of smoke and gases as water is converted from a liquid to a vaporCrapid contraction as water is converted from a liquid to a vaporDrapid expansion as water absorbs heat and changes to steam
单选题The dew point is reached when the（）.Atemperature of the air equals the temperature of the seawaterBatmospheric pressure is 14.7 lbs. per square inchCrelative humidity reaches 50%Dair becomes saturated with water vapor
问答题Practice 1 Heat loss by sweating depends on the fact that when a liquid evaporates, it absorbs an enormous quantity of heat from its surroundings. Therefore, when I am of sweat evaporate, a great deal of heat is absorbed from the surface of the body in contact with it. 1______ 2______ The first is the amount of movement of air surrounding the body. The second is the amount of water vapor in the air that surrounds the body. 3______ For this reason, sweat evaporates very rapidly on windy days, and the rate of heat loss by sweating is much more than on a still day. This accounts for the fact that hot still days are much less comfortable than hot windy days. In contrast, the sweat evaporates very rapidly on hot windy days, and cools the body quickly and effectively. 4______ When air is carrying the maximum amount of water vapor that it can hold, it is said to be 100% saturated with water vapor. The relative humidity of the air is said to be 100%. Under these conditions the air cannot carry any water, so no water can evaporate. When the relative humidity is high, therefore, sweat cannot evaporate. Instead, it forms large drops and runs off your skin without cooling you. 5______ It is obvious that under these conditions, evaporation will be much more rapid. Therefore, sweating will be much more effective as a method of losing heat from the body. On a hot dry day, sweat evaporates as soon as it is formed, and you feel reasonably cool even though the temperature of your environment is very high.[A] When the air is very dry and carries no water at all, the relative humidity is said to be 0%.[B] The second factor is the amount of water vapor in the air－the humidity.[C] Hot windy days are much more comfortable than hot still days.[D] This heat transfer occurs even if the environment is hotter than the body.[E] When air moves over the surface of water, the amount of evaporation is greatly increased.[F] You might expect the highest incidence of a heat stroke when the maximum temperature is 100 and humidity is 50%.[G] Two factors affect the rate of evaporation of sweat, and therefore the effectiveness of sweating as a method of cooling the body.
单选题If you were operating a centrifugal water service pump with worn wearing rings, the （）.Apump would be very noisyBpump would vibrate excessivelyCpump would develop insufficient flowDstuffing box would leak excessively
单选题A racetrack turn would be better than a Williamson turn in recovering a man overboard if （）.Athe man has been missing for a period of timeBthe sea water is very cold and the man is visibleCthere is thick fogDthe wind was from astern on the original course
单选题If you burned your arm on a bare steam line, the most effective immediate treatment would be to（）Awrap the arm in a tight bandageBsoak the arm in hot salt waterCcover the burn with petroleum jellyDput the burn in cold water
单选题A rectangular fish tank has a base 2 feet wide and 3 feet long. When the tank is partially filled with water, a solid cube with an edge length of 1 foot is placed in the tank. If no overflow of water from the tank is assumed, by how many inches will the level of the water in the tank rise when the cube becomes completely submerged?A1/6B1/2C2D3E4
单选题Fighting a rig fire in the ballast pumproom with hoses would adversely affect the stability of the rig most by（）.Aincreasing the permeability of the pumproomBreduction of drill water from the storage tanksCa list caused by water filling the compartmentDa reduced KG caused by water filling the compartment