看了几道大牛说是750水平的题，各位看看难度如何（附答案）？

Gravity18

Q82 Technological improvements and reduced equipment costs have made converting solar energy directly into electricity far more cost-efficient in the last decade. However, the threshold of economic viability for solar power (that is, the price per barrel to which oil would have to rise in order for new solar power plants to be more economical than new oil-fired power plants) is unchanged at thirty-five dollars.
Which of the following, if true, does most to help explain why the increased cost-efficiency of solar power has not decreased its threshold of economic viability?
A. The cost of oil has fallen dramatically.
B. The reduction in the cost of solar-power equipment has occurred despite increased raw material costs for that equipment.
C. Technological changes have increased the efficiency of oil-fired power plants.
D. Most electricity is generated by coal-fired or nuclear, rather than oil-fired, power plants.
E. When the price of oil increases, reserves of oil not previously worth exploiting become economically viable.
(Ans: C)
I wonder what is the difference between options A & C?

Q100 Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacterium while in the larval stage by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.
Which of the following would it be most important to ascertain in evaluating the argument?
A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice
B. Whether the size of the deer tick population is currently limited by the availability of animals for the tick’s larval stage to feed on
C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice
D. Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed
E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans
(Ans: B)

Q108) 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 with animals, the percentage with animal-induced allergies is not 30 percent but substantially more.
Which of the following, if true, provides 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.
(Ans: A)
I have problem understanding why the allergy rate is 30% or more of the exposed members of general population (group A), isn’t it saying 30% is of the employees in zoos (group B). I suppose they are not the same groups?

Gravity18

下面是答案解析

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Timochan

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