31. In context，which of the following revisions of the underlined portion of sentence 4(reproduced below)would add the most relevant information?

　　But by the late 1970s，closer observation had established that Pluto was in fact less than half the size of Mercury.

　　(A) Mercury，the planet closest to the Sun

　　(B) Mercury，the smallest of the traditional planets

　　(C) Mercury，which was named for a Roman messenger god

　　(D) Mercury，which was discovered in ancient times

　　(E) Mercury，whose atmosphere is too thin to support human life

　　答案：B

　　解析：Sentence 5：一些天文学家质疑Pluto太小，认为它不能算作行星。Sentence 4：Pluto比Mercury的一半还小，此处添加的内容必须要凸显Pluto太小，与其他的planets的大小相差过大，从而与Sentence 5相联系，与整段逻辑一致。B：Mercury是traditional planets中最小的，也就是说，Pluto与traditional planets的大小相差过大，符合题目要求。其他选项属于无关选项。

　　32. Which of the following sentences，if inserted immediately before sentence 6，would provide the most effective transition between the first and second paragraphs ?

　　(A) Pluto’s anomalous size was not the only source of doubt.

　　(B) This was not the first time that a planet’s status has been called into question.

　　(C) Such scientific disputes can become surprisingly heated.

　　(D) The question of who deserves credit for a scientific discovery is sometimes difficult to settle.

　　(E) Many were shocked at the suggestion that Pluto was not really a planet.

　　答案：A

　　解析：第一段的Sentence 5提出Pluto受到质疑的一个原因：too small;第二段的Sentence 6提出第二个原因：composed of ice。A：size不是唯一质疑，符合上下句;B、C与下文无关;D选项与上下文均无关。此处已经提到了质疑的两方面，E选项中“Pluto有可能不是行星，这个说法让很多人震惊了”，与上下文的内容不符。

　　33. In context，which of the following is the best revision of the underlined portion of sentence 7(reproduced below)?

　　In the 1990s it was discovered that Pluto was just the largest of hundreds of comet-like bodies occupying a region known as the Kuiper Belt.

　　(A) In the 1990s，however，

　　(B) In the 1990s，by comparison

　　(C) In fact，in the 1990s

　　(D) Similarly，in the 1990s

　　(E) Consequently，in the 1990s

　　答案：C

　　解析：Sentence 6提出第二个质疑：composed of ice，Sentence 7 Pluto是许许多多的comet-like bodies中最大的，Sentence 7 更进一步说明Pluto与其他bodies相似，从而不能算作planets。AB的转折关系错误;E的因果关系错误，原文没有“因此”这层意思，Sentence 7是事实，不是结论。C的“In fact”符合题目要求。D的similarly：同样地，Sentence 7与Sentence 6没有进行比较。