请教陈向东的三道题

假设题部分:

7.last year,support for the social sciences represented only about three percent of the government's total buget for reaserch funds in the U.S. Thus, the particularly sharp reductions imposed on such programs this year seem dictated not by financial constraints but by social philosophy.

which of the following is an assumption on which the conclusion above is drawn?

D.government funding is the primary source of reaserch money in the U.S

E.three percent is an insignificant portion of the government's total buget for the reaserch funds

8 it has been hypothesized that much of the matter in the universe is "dark",i.e,unseen. Studies have shown that galaxies in many galaxy clusters are moving faster with respect to one another than they would if visible stars constituted all their mass. the studies suggest that the galaxies are moving under the gravitational influences of unseen mass in considerable quantity.

which of the following is an assumption underlying the passage above?

C. the aggregate mass of visible stars in the galaxies mentioned above can be estimated with some confidence.

D. the general composition of unseen matter in the universe has been determined.

15 in 1985,a consumer agency concluded that X brand bicycle are safer to ride than are Z brand bicycles. The agency based the conclusion on the ratio of the number of rider injuries to the number of riding hours for each brand of bicycles from 1981 through 1984. Yet for identically designed bicycles manufactured since 1985,the number of rider injuries has been twice as great among riders of X as among riders of Z. therefore, the agency 's  conclusion would have been different for the period since 1985.

which of the following is an assumption that, if true, supports the claim that the agency's conclusion would have been different for the period since 1985?

A. for the peroid since 1985, the number of riding hours for Z totoaled at least half the number of riding hours for X

B.of all the bicycles ridden in the period since 1985, the percentage of Xwas twice the percentage of Z ridden.

我的问题是:

7题原文是陈所谓的"B,A"模式,hidden premise 应是A是B的唯一原因或方式,照这样的思路应是D, 而E是着眼在redution上

8题请NN翻译下红字部分,这道题为什么选C啊?

15题黄字部分是个虚拟吗?那应该是和现实相反吧?

题给两个答案有什么区别呢?偶对有比例的问题都搞不清楚,请NN指教这样的题的解法

多谢!

可以解答一下吗?

初次发帖没有按照格式来,不好意思

请牛牛解答下吧