If a diver surfaces too quickly, he may suffer the bends. Nitrogen(氮) dissolved(溶解) in his blood is suddenly liberated by the reduction of pressure. The consequence, if the bubbles (气泡)accumulate in a joint, is sharp pain and a bent body—thus the name. If the bubbles form in his lungs or his brain, the consequence can be death.
Other air-breathing animals also suffer this decompression(减压) sickness if they surface too fast: whales, for example. And so, long ago, did ichthyosaurs. That these ancient sea animals got the bends can be seen from their bones. If bubbles of nitrogen form inside the bone they can cut off its blood supply. This kills the cells in the bone, and consequently weakens it, sometimes to the point of collapse. Fossil (化石)bones that have caved in on them selves are thus a sign that the animal once had the bends.
Bruce Rothschild of the University of Kansas knew all this when he began a study of ichthyosaur bones to find out how widespread the problem was in the past. What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompression over the 150 million years. To this end, he and his colleagues traveled the world’s natural-history museums, looking at hundreds of ichthyosaurs from the Triassic period and from the later Jurassic and Cretaceous periods.
When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression. Instead, he was astonished to discover the opposite. More than 15% of Jurassic and Cretaceous ichthyosaurs had suffered the bends before they died, but not a single Triassic specimen(标本) showed evidence of that sort of injury.
If ichthyosaurs did evolve an anti-decompression means, they clearly did so quickly—and, most strangely, they lost it afterwards. But that is not what Dr Rothschild thinks happened. He suspects it was evolution in other animals that caused the change.
Whales that suffer the bends often do so because they have surfaced to escape a predator (捕食动物) such as a large shark. One of the features of Jurassic oceans was an abundance of large sharks and crocodiles, both of which were fond of ichthyosaur lunches. Triassic oceans, by contrast, were mercifully shark- and crocodile-free. In the Triassic, then, ichthyosaurs were top of the food chain. In the Jurassic and Cretaceous, they were prey(猎物) as well as predator—and often had to make a speedy exit as a result.
1.Which of the following is a typical symptom of the bends?
A. A twisted body. B. A gradual decrease in blood supply.
C. A sudden release of nitrogen in blood. D. A drop in blood pressure.
2.The purpose of Rothschild’s study is to see________ .
A. how often ichthyosaurs caught the bends B. how ichthyosaurs adapted to decompression
C. why ichthyosaurs bent their bodies D. when ichthyosaurs broke their bones
3.Rothschild’sfindingstatedinParagraph4 .
A. confirmed his assumption B. speeded up his research process
C. disagreed with his assumption D. changed his research objectives
4.Rothschild might have concluded that ichthyosaurs.
A. failed to evolve an anti decompression means
B. gradually developed measures against the bends
C. died out because of large sharks and crocodiles
D. evolved an anti decompression means but soon lost it
高二英语阅读理解中等难度题
If a diver surfaces too quickly, he may suffer the bends. Nitrogen(氮) dissolved(溶解) in his blood is suddenly liberated by the reduction of pressure. The consequence, if the bubbles (气泡)accumulate in a joint, is sharp pain and a bent body—thus the name. If the bubbles form in his lungs or his brain, the consequence can be death.
Other air-breathing animals also suffer this decompression(减压) sickness if they surface too fast: whales, for example. And so, long ago, did ichthyosaurs. That these ancient sea animals got the bends can be seen from their bones. If bubbles of nitrogen form inside the bone they can cut off its blood supply. This kills the cells in the bone, and consequently weakens it, sometimes to the point of collapse. Fossil (化石)bones that have caved in on them selves are thus a sign that the animal once had the bends.
Bruce Rothschild of the University of Kansas knew all this when he began a study of ichthyosaur bones to find out how widespread the problem was in the past. What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompression over the 150 million years. To this end, he and his colleagues traveled the world’s natural-history museums, looking at hundreds of ichthyosaurs from the Triassic period and from the later Jurassic and Cretaceous periods.
When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression. Instead, he was astonished to discover the opposite. More than 15% of Jurassic and Cretaceous ichthyosaurs had suffered the bends before they died, but not a single Triassic specimen(标本) showed evidence of that sort of injury.
If ichthyosaurs did evolve an anti-decompression means, they clearly did so quickly—and, most strangely, they lost it afterwards. But that is not what Dr Rothschild thinks happened. He suspects it was evolution in other animals that caused the change.
Whales that suffer the bends often do so because they have surfaced to escape a predator (捕食动物) such as a large shark. One of the features of Jurassic oceans was an abundance of large sharks and crocodiles, both of which were fond of ichthyosaur lunches. Triassic oceans, by contrast, were mercifully shark- and crocodile-free. In the Triassic, then, ichthyosaurs were top of the food chain. In the Jurassic and Cretaceous, they were prey(猎物) as well as predator—and often had to make a speedy exit as a result.
1.Which of the following is a typical symptom of the bends?
A. A twisted body. B. A gradual decrease in blood supply.
C. A sudden release of nitrogen in blood. D. A drop in blood pressure.
2.The purpose of Rothschild’s study is to see________ .
A. how often ichthyosaurs caught the bends B. how ichthyosaurs adapted to decompression
C. why ichthyosaurs bent their bodies D. when ichthyosaurs broke their bones
3.Rothschild’sfindingstatedinParagraph4 .
A. confirmed his assumption B. speeded up his research process
C. disagreed with his assumption D. changed his research objectives
4.Rothschild might have concluded that ichthyosaurs.
A. failed to evolve an anti decompression means
B. gradually developed measures against the bends
C. died out because of large sharks and crocodiles
D. evolved an anti decompression means but soon lost it
高二英语阅读理解中等难度题查看答案及解析
If you use too much force, you’ll _______ the key, bending it out of shape.
A. break B. seize
C. twist D. split
高二英语单项填空困难题查看答案及解析
Do you have such kind of experience?In a bus you may look at a stranger,but not too long.And if he senses that he1.(stare) at,he may feel uncomfortable.
The same happens in daily life.If you are looked at for more than necessary,you will look at yourself up and down,to see2.anything is wrong with you.If nothing goes wrong,you will feel uncomfortable.Eyes do speak,right?
3.(look) too long at someone may seem to be rude.But things are different when4.comes to a stare at the opposite sex.If a man5.(glance) at a woman for more than 10 seconds,that means he wishes to make her know he is admiring her.Normally,the speaker in conversation will look at the listener at times to make sure that the listener does pay attention to6.the former is saying.A poor liar usually makes himself7.(expose) by looking too long at the victim,since he believes in the false idea that to look straight in the eye is a sign of honest8.(communicate). Actually,continuous eye contact exists in lovers only,who will enjoy looking at each other gently for a long time to show love that words cannot convey.
9.(evident),eye contact should be done according to the specific situation and the relationship10.the two people.
高二英语短文填空困难题查看答案及解析
If only he________quietly as the doctor instructed, he wouldn’t suffer so much now.
A. lies B. lay C. should lie D. had lain
高二英语单项填空中等难度题查看答案及解析
Please do not feed the fish; they _____ die if they eat too much.
A.shall | B.must | C.need | D.may |
高二英语单项填空中等难度题查看答案及解析
Please do not feed the fish; they ________ die if they eat too much.
A.shall B.must C.may D.need
高二英语单项填空中等难度题查看答案及解析
If he hadn’t hesitated for a moment before kicking the ball, he a goal.
A.may have scored B.would score C.would have scored D.had scored
高二英语单项填空困难题查看答案及解析
Marty is a disabled boy 1. suffers from a muscle disease. Sometimes he is too weak 2.(run) or climb stairs as quickly as other people. The doctors don’t know 3. (exact) what is wrong with him. Luckily, Marty has learned to adapt 4. his disability. In order to make his life happy and 5. (satisfy), Marty keeps busy doing things that do not require physical strength. He has friends with 6. he can go to movies and football matches and he has lots of pets. He used to dream of one day being a famous football player and 7. (represent) his country in the World Cup. Even when he is made fun of, he doesn’t get 8. (annoy). Disabled 9. he is, Marty has become stronger and more independent. He never feels sorry for himself and he enjoys as rich and full a life as everyone else.
He suggests that we normal people should give the disabled 10. (encourage) rather than laugh at them.
高二英语语法填空中等难度题查看答案及解析
If Peter ________ harder in the senior high school, he would be a college student now, too.
A. had worked B. have worked
C. should work D. worked
高二英语单项填空中等难度题查看答案及解析
Was it the restaurant where he had dinner with me, if I may ask, _______offered him a job?
A.that B.where C.which D.when
高二英语单项填空中等难度题查看答案及解析