求高人指点-XDF-29，XDF-209，XDF-235

XDF-29

People who have spent a lot of time in contact with animals often develop animal-induced allergies, some of them quite serious. In a survey of current employees in major zoos, about 30 percent had animal-induced allergies.  Based on this sample, experts conclude that among members of the general population who have spent a similarly large amount of time in close contact of animals, the percentage with animal-induced allergies is not 30 percent but substantially more.

Which of the following, if true, provide the strongest grounds for the experts’ conclusion?

A)      A zoo employee who develops a serious animal-induced allergy is very likely to switch to some other occupation.

B)      A zoo employee is more likely than a person in the general population to keep one or more animal pets at home.

C)      The percentage of the general population whose level of exposure to animals matches that of a zoo employee is quite small.

D)      Exposure to domestic pets is, on the whole, less likely to cause animal-induced allergy than exposure to many of the animals kept in zoos.

E)      Zoo employees seldom wear protective gear when they handle animals in their care.

答案：A

我的问题：我对A里面说的some other occupation不太理解，这里说的职位是动物园里的职位，还是动物园外的职位呀。如果是动物园外的，算过敏率的时候这些在动物园里过敏的人是不是还要再被当作普通人群再被计算一次呀？要不然为什么普通人群里过敏的比例还要高呢？

应该是其他职业，不是职位。

XDF-209

Manatees, aquatic mammals inhabiting to the surface and are frequently killed in collisions with boats.  To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds.  Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows.  Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A)      The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported collisions between manatees and boats.

B)      Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat traffic.

C)      Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the endangered manatee population.

D)      The sound of a boat engine generally travels much further under water than it does through the air.

E)      When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal background noise.

答案：E

我的问题：我觉得B更象正确答案吧，这样不是削弱得更彻底一些吗？E里面，我觉得over normal background noise很有问题。文章里面根本没有涉及船的噪音和背景噪音的比较呀。

结论中的make things中的things是指problem，即Manatees, aquatic mammals inhabiting to the surface and are frequently killed in collisions with boats，而不是Manatees生活环境什么的。E削弱的是结论的理由：manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows. 不成立。

XDF-235

Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants.  The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord.  Antibodies that deactivate those inhibitors have now been developed.  Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.

Which of the following, if true, casts the more serious doubt on the accuracy of the prediction above?

A)      revention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.

B)      Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.

C)      Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally.

D)      Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.

E)      Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.

答案：A

我的问题：虽然其他选项也不象正确答案，可是A也太牵强了点吧。文章里说antibodies可以抑制inhibitors，但也没说是抑制它的主要作用还是次要作用啊。按照A的逻辑，也就是说antibodies已经被预定义为只能抑制主要或次要作用当中的一种，不是太没根据了吗？