117. A certain viral infection is widespread among children, and about 30 percent of children infected with the virus develop middle ear infections. Antibiotics, although effective in treating bacterial infections, have no effect on the virus. Yet when middle ear infections in children infected with the virus are treated with antibiotics, the ear often clear up.
Which one of the following most helps to explain the success of the treatments with antibiotics?
(A) Although some types of antibiotics fail to clear up certain infections, other types of antibiotics might provide effective treatment for those infections.
(B) Children infected with the virus are particularly susceptible to bacterial that infect the middle age.
(C) Many children who develop middle ear infections are not infected with the virus.
(D) Most viral infections are more difficult to treat than are most bacterial infections.
(E) Among children not infected with the virus, fewer than 30 percent develop middle ear infections.
122. Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, it one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.
The conclusion of the argument is properly drawn it which one of the following is assumed?
(A) the cost of producing electric power at traditional plants has increased over the past 20 years.
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 10 times the cost of producing power at traditional plants.
(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.
answer: B, D
This question requires to be identified an assumption that would allow the argument’s conclusion to be properly drawn. As the argument is stated, there is a logical gap between the information given in the premises and the claim made in the conclusion:
Premise1: The cost of producing electric power at photovoltaic power plants is one-tenth of what it was 20 years ago.
Premise 2: The corresponding cost for traditional plants has increased.
Conclusion: Photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do tranditional power plants.
From the fact that one cost has gone down while another has risen, it does not necessarily follow that the first is now lower than the second. In particular, if the cost of producing electric power at photovoltaic power plants twenty years ago was more than then times the corresponding cost for traditional plants, then the fact that it is now one-tenth what it was is not sufficient to show that it is now lower than the corresponding cost for traditional plants, even though we are told in Premise 2 that the cost for traditional plants has increased. To conclude from the premises given in the argument that photovoltaic power plants now offer a less expensive approach than do traditional power plants, we need to know how the costs of the two methods of production were related 20 years ago – specifically that the cost of producing power at photovoltaic plants was less than 10 times the cost of producing it at traditional plants. (D) gives this information and is, thus, the credited response.
A. is incorrect because it tells us about only one of the two costs, not about how the two were related 20 years ago. It in effect restates premise 2, and premises 1 and 2 together are not sufficient for drawing the conclusion.
B. is incorrect. The amount of electricity produced by the different kinds of plants is not at issue.
C. is incorrect. While it is relevant tothe discussion, (C) does not provide the information about the comparative costs of the two kinds of plants 20 years ago that allows the conclusion to be properly drawn.
D. is incorrect because the conclusion in the argument is about the present only. Whether or not the change described in (E) is expected to take place has no bearing on the claim in the conclusion that the one kind of plant offers a less expensive approach at present.
117. A certain viral infection is widespread among children, and about 30 percent of children infected with the virus develop middle ear infections. Antibiotics, although effective in treating bacterial infections, have no effect on the virus. Yet when middle ear infections in children infected with the virus are treated with antibiotics, the ear often clear up.
Which one of the following most helps to explain the success of the treatments with antibiotics?
(A) Although some types of antibiotics fail to clear up certain infections, other types of antibiotics might provide effective treatment for those infections.
(B) Children infected with the virus are particularly susceptible to bacterial that infect the middle age.
(C) Many children who develop middle ear infections are not infected with the virus.
(D) Most viral infections are more difficult to treat than are most bacterial infections.
(E) Among children not infected with the virus, fewer than 30 percent develop middle ear infections.
这题我选B。我的理解是，题目要求解释，为什么antibiotic能治疗这个middle ear infection.文章中说，antibiotic能treat bacterial infection，但不能treat导致middle ear infections的virus。所以我们就找把bacterial和virus中间搭座桥的选项。很明显是B。
122. Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, it one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.
The conclusion of the argument is properly drawn it which one of the following is assumed?
(A) the cost of producing electric power at traditional plants has increased over the past 20 years.
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 10 times the cost of producing power at traditional plants.
(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.
这题我选D。理由是，文章中绿色部分是作者的推理过程，他说p植物的成本是20年前的1/10，而traditional植物成本上升，推出p植物less expensive。所以需要在前2者中间建立关系。D选项就告诉我们20年前p植物的成本比traditional植物成本的10倍少，所以1/10的p植物成本少于traditonal植物，那自然比提高了的traditonal植物的成本更少。并且可以用not+weaken来验证。
罗嗦了半天，不知道说清楚没有。。见谅见谅。。。melissasun 同学解释的很清楚，这俩题中规中矩，是两个好典型题目！
117
C----->B
A----\----C
so A----->B B is the gap or bridge
中文的解释比英文清楚多了！
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