Question

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 themselves 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.

61. 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.

62. 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

63. Rothschild’s finding stated in Paragraph 4 ______.

A. confirmed his assumption                    B. speeded up his research process

C. disagreed with his assumption            D. changed his research objectives

64. 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

Answer 1

语篇解读：本篇为科普说明文，讲的鱼龙的身体弯曲的原因和后果。Dr Rothschild通过实验推翻了关于鱼龙进化的一些猜测。

段落	关键词、句	大意概括
第一部分 （Para. 1-2）	Nitrogen dissolved; the reduction of pressure; sharp pain and a bent body; death; Other air-breathing animals; decompression; sickness	压力减少导致的氮溶解；结果时剧痛和弯曲，甚至死亡。其它动物也会遭受减压疾病。
第二部分 （Para. 3-6）	Rothschild began a study; he assumed…; Instead, he was astonished to discover…; he suspects…	Rothschild开始一项调查；他先假设；然后惊奇发现结果并非如此；他怀疑……

61. A。细节理解题。根据the bends可定位到首段。由The consequence…is sharp pain and a bent body—thus the name.可知答案，a bent body和a twisted body是同义转换。由第二句的“…suddenly liberated by the reduction of pressure.”可知这是说the bends的形成原因，故C和D项错，而B项文章没有提及。

62. B。推理判断题。题干中的关键词是Rothschild’s study。由此可定位到第三段的前两句。根据to find out how widespread the problem was in the past和to investigate was how ichthyosaurs adapted to the problem of decompression可知答案为B。其它各项与Rothschild’s study没有关系。

63. C。推理判断题。第四段开始说到he assumed that signs of the bends would be rarer in younger fossils，接下来又说Instead, he was astonished to discover the opposite。可见，他的实验结果和他开始的预测相反，故C项符合。instead是一个转换话题的标志词，一般为题眼所在。

64. A。推理判断题。由倒数第二段的If ichthyosaurs did evolve an anti-decompression means…But that is not what Dr Rothschild thinks happened.可知，Dr Rothschild并不认可鱼龙的抗溶解进化途径。故A项符合。B项文章没有提及；文章只是说they have surfaced to escape a predator，并不是说鱼龙的灭绝是鲨鱼造成的；D项与Dr Rothschild的看法正好相反。

【难句学习】

1. The consequence, if the bubbles (气泡) accumulate in a joint, is sharp pain and a bent body—thus the name.

翻译：如果气泡在一个关节处累积，后果就是剧痛和弯曲的身体——因此它的名字就这样产生了。

分析：本句中的if引导的状语从句是插入语，主干是The consequence is sharp pain and a bent body。

2. 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.

翻译：开始时，他假设弯曲的迹象在年纪轻的化石中会少见，这也反映在针对减压的措施中他们的逐渐进化。

分析：本句主干是he assumed that…。when引导时间状语从句，reflecting是现在分词结构作结果状语。