feifei-70

A low-pressure weather system is approaching Plainville; rainfall results from about 70 percent of such systems in the Plainville area. Moreover, the current season, spring, is the time of year in which thundershowers, which sometimes result from low-pressure systems, are most likely to occur in Plainville.

Knowing which one of the following, in addition to the information above, would be most useful for determining the probability that Plainville will have a thundershower soon?

(A) the percentage of thundershowers in Plainville that occur in the spring

(B) the percentage of spring rainfalls in Plainville that are thundershowers

(C) the percentage of thundershowers in Plainville that result from low-pressure systems

(D) whether low-pressure systems in other areas are associated with rainfall（B）

(E) whether Plainville has more or fewer thundershowers each spring than do nearby towns

请问答案到底是B还是C? 我的资料上一个说是B, 一个说是C 而我觉着它们两个都对 请帮忙指点一下推理过程, 谢谢!

原文：现在低压天气正靠近。70%低压天气有rainfall。现在正是spring

B。spring rainfall的百分之多少几率是thundershowers。这样就知道了thundershower的可能性。

C的意思为thundershower百分之几可能性来之于低压天气。如果改为低压天气的百分之几可能性产生thundershower。则为答案。请细心体会其区别。关键看percentage修饰那个。

一语中的!!! 明白了 我读题太粗,再加上feifei的解释是C,就糊涂了! 相信feifei的解释是错的.

豁然开朗！