单选题Freshwater fish stocks are vulnerable or endangered because of ______.Ashortage of freshwater.Bpollution and changes in their living environment.Cfertilizer run-off.Dclosed chemical works.
单选题
Freshwater fish stocks are vulnerable or endangered because of ______.
A
shortage of freshwater.
B
pollution and changes in their living environment.
C
fertilizer run-off.
D
closed chemical works.
参考解析
解析：
从录音最后提到的超过五分之一的淡水鱼已经变得“vulnerable or endangered because of pollution or habitat modification”，可见污染和生存环境的变化是淡水鱼变得易受伤害或濒临灭绝的原因。
【录音原文】
Sheer shortages of freshwater are not the only problem. Fertilizer run-off and chemical pollution threaten both water quality and public health. More than one fifth of freshwater fish stocks are already vulnerable or endangered because of pollution or habitat modification.
从录音最后提到的超过五分之一的淡水鱼已经变得“vulnerable or endangered because of pollution or habitat modification”，可见污染和生存环境的变化是淡水鱼变得易受伤害或濒临灭绝的原因。
【录音原文】
Sheer shortages of freshwater are not the only problem. Fertilizer run-off and chemical pollution threaten both water quality and public health. More than one fifth of freshwater fish stocks are already vulnerable or endangered because of pollution or habitat modification.
相关考题：
Text 3When prehistoric man arrived in new parts of the world, something strange happened to the large animals. They suddenly became extinct. Smaller species survived. The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.That the seas are being overfished has been known for years. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) in a new fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.Dr. Worm acknowledges that the figures are conservative. One reason for this is that fishing technology has improved. Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago. That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines would have been more saturated with fish. Some individuals would therefore not have been caught, since no baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around now.Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline.” The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels. Most fisheries are well below that, which is a bad way to do business.31. The extinction of large prehistoric animals is noted to suggest that ________.[A] large animal were vulnerable to the changing environment[B] small species survived as large animals disappeared[C] large sea animals may face the same threat today[D] slow-growing fish outlive fast-growing ones
We will _________ all kinds of pollution(污染) control methods to protect our living conditions. A、extraB、accordingC、costD、enforce
If the coolant temperature of a closed cooling water system for a diesel enginegradually increases, the trouble usually is( ).A.a broken shaft on the freshwater pumpB.an excessive accumulation of scale in the heat exchangerC.an incorrect thermostatic element operating rangeD.lube oil in the cooling water
In a diesel engine closed freshwater cooling system, the amount of coolant flowing through the heat exchanger is controlled by the __.A.suction pressure regulatorB.thermostatic bypass valveC.sea water temperatureD.water level in the expansion tank
The systems of universities are very vulnerable because they are decentralized and accessible to many people.
共用题干第二篇Night of the Living AntsWhen an ant dies,other ants move the dead insect out of the nest.This behavior is interesting to scien-tists,who wonder how ants know for sure一and so soon一that another ant is dead.Dong-Hwan Choe,a scientist at the University of California,found that Argentine ants have a chemical on the outside of their bodies that signals to other ants,"I'm dead一take me away."But there's a twist to Choe's discovery. These ants behave a little bit like zombies（僵尸）.Choe says that the living ants一not just the dead ones一have this death chemicals. In other words,while an ant crawls around,perhaps in a picnic or home,it's telling other ants that it's dead.What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies,and these tell nearby ants something like,"Wait一I'm not dead yet."So Choe's research turned up two sets of chemical signals in ants:one says,"I'm dead,"the other set says,"I'm not dead yet."Other scientists have tried to figure out how ants know when another ant is dead.If an ant is knockedunconscious,other ants leave it alone until it wakes up.That means ants know that unmoving ants can still be alive.Choe suspects that when an Argentine ant dies,the chemical that says"Wait一I'm not dead yet"quickly goes away. Once that chemical is gone,only the one that says"I'm dead"is left."It's because the dead ant no longer smells like a living ant that it gets carried to the graveyard（墓地）,not because its body releases new,unique chemicals after death,"said Choe.When other ants detect the"dead"chemical without the"not dead yet" chemical,they haul away the body. This was Choe's hypothesis（假设）.To test his hypothesis,Choe and his team put different chemicals on Argentine ant pupae（蛹）.When the scientists used the"I'm dead"chemical,other ants quickly hauled the treated pupae away.When the sci-entists used the"Wait一I'm not dead yet"chemical,other ants left the treated pupae alone.Choe believes this behavior shows that the" not dead yet" chemical overrides（优先于）the" dead" chemical when picked up by adult ants.And that when an ant dies,the"not dead yet"chemical fades away.Other nearby ants then de-tect the remaining"dead"chemical and remove the body from the nest.According to Choe's hypothesis,_______________.A:an ant still smells like a living one when it diesB:the"I am dead"chemical leaves the ant's body when it diesC:the"I am not dead yet"chemical is left when an ant diesD:the"I am not dead yet"chemical quickly goes away when it dies
共用题干第二篇Night of the Living AntsWhen an ant dies,other ants move the dead insect out of the nest.This behavior is interesting to scien-tists,who wonder how ants know for sure一and so soon一that another ant is dead.Dong-Hwan Choe,a scientist at the University of California,found that Argentine ants have a chemical on the outside of their bodies that signals to other ants,"I'm dead一take me away."But there's a twist to Choe's discovery. These ants behave a little bit like zombies（僵尸）.Choe says that the living ants一not just the dead ones一have this death chemicals. In other words,while an ant crawls around,perhaps in a picnic or home,it's telling other ants that it's dead.What keeps ants from hauling away the living dead? Choe found that Argentine ants have two additional chemicals on their bodies,and these tell nearby ants something like,"Wait一I'm not dead yet."So Choe's research turned up two sets of chemical signals in ants:one says,"I'm dead,"the other set says,"I'm not dead yet."Other scientists have tried to figure out how ants know when another ant is dead.If an ant is knockedunconscious,other ants leave it alone until it wakes up.That means ants know that unmoving ants can still be alive.Choe suspects that when an Argentine ant dies,the chemical that says"Wait一I'm not dead yet"quickly goes away. Once that chemical is gone,only the one that says"I'm dead"is left."It's because the dead ant no longer smells like a living ant that it gets carried to the graveyard（墓地）,not because its body releases new,unique chemicals after death,"said Choe.When other ants detect the"dead"chemical without the"not dead yet" chemical,they haul away the body. This was Choe's hypothesis（假设）.To test his hypothesis,Choe and his team put different chemicals on Argentine ant pupae（蛹）.When the scientists used the"I'm dead"chemical,other ants quickly hauled the treated pupae away.When the sci-entists used the"Wait一I'm not dead yet"chemical,other ants left the treated pupae alone.Choe believes this behavior shows that the" not dead yet" chemical overrides（优先于）the" dead" chemical when picked up by adult ants.And that when an ant dies,the"not dead yet"chemical fades away.Other nearby ants then de-tect the remaining"dead"chemical and remove the body from the nest.What is meant by"death chemical"mentioned in Paragraph 3?A:A chemical that contains poison.B:A chemical that causes death.C:A chemical that announces death.D:A chemical that prevents death.
A Unclean B/L may be issued because of （）.A、damage to cargoesB、improper packingC、late deliveryD、shortage of cartons
单选题Freshwater fish stocks are vulnerable or endangered because of ______.Ashortage of freshwater.Bpollution and changes in their living environment.Cfertilizer run-off.Dclosed chemical works.
问答题Pollution 1)Pollution is a problem because man, in an increasingly populated and industrialized world，is upsetting the environment in which he lives. 2) Many scientists maintain that one of man's greatest errors has been to equate growth with advancement. 3) Now “growth” industries are being looked on with suspicion incase their side effects damage the environment and disrupt the relationship of different forms of life. 4) The growing population makes increasing demands on the world’s fixed supply of air, water and land. 5) This rise in population is accompanied by the desire of more and more people for a better standard of living. 6) The problem has been causing increasing concern to living things and their environment.
单选题If the coolant temperature of a closed cooling water system for a diesel engine gradually increases, the trouble usually is （）Aa broken shaft on the freshwater pumpBan excessive accumulation of scale exchangerCan incorrect thermostatic element operating rangeDlube oil in the cooling water
单选题The highest pressure in any closed diesel engine freshwater cooling system is at the （）.Ajacket water outletBexpansion tank inletCheat exchanger inletDcooling water pump outlet
单选题In any diesel engine closed freshwater cooling system, the lowest pressure exists at the （）.Ajacket water outletBcooling water pump outletCheat exchanger outletDexpansion tank atmospheric vent
单选题The Master should call （） for permission to use chemical agents in response to oil pollution into sea.Athe flag stateBthe coastal stateCthe port stateDthe shipping company
单选题The outlet from an expansion tank of a closed freshwater cooling system should be piped to the （）.Acylinder head water outlet headerBcylinder jacket inlet mainCheat exchanger inlet connectionDjacket water pump suction line
填空题In warm and mild regions, farmed fish and shellfish are also affected by POPs because they are fed fish meal.____
单选题Which of the following is a disadvantage of living in a cosmopolitan city, according to the passage?AThe pollution.BThe traffic congestion.CThe high cost of living.DThe population decrease.
单选题In a closed diesel engine freshwater cooling system, the amount of coolant flowing through the heat exchanger is controlled by the （）.Asuction pressure regulatorBthermostatic bypass valveCsea water temperatureDwater level in the expansion tank
单选题The Atlantic coast of Patagonia is increasingly vulnerable. Squid fishing is depleting food stocks vital to marine life.Aessential Bpreliminary Csophisticated Dsheer
单选题The jacket water temperature in a diesel engine closed freshwater cooling system is normally controlled by （）Aregulating the level of corrosion inhibitor in the primary cooling systemBthe level of the freshwater expansion tankCvarying the engine load to meet temperature requirementsDthe operation of the thermostatic valve
单选题The expansion tank in a diesel engine closed freshwater cooling system is located at （）Athe highest point in the systemBthe lowest point in the systemCnear the floorDplate level or near the tank top level
单选题Operating a diesel engine for prolonged periods, with a closed freshwater cooling system, at temperatures lower than the normal design temperature can cause （）.Athe formation of sulfuric acidBa decrease in lube oil viscosityCa decrease in cooling water pHDa thermostat failure
单选题Why are elephants endangered?AThey are changing living habits.BThey are driven into thick forests.CTwo species of disease threaten their lives.DDemand from ivory market leads to their killing.