单选题 When imaginative men turn their eyes towards space and wonder whether life exists in any part of it, they may cheer themselves by remembering that life need not resemble closely the life that exists on Earth. Mars looks like the only planet where life like ours could exist, and even this is doubtful. But there may be other kinds of life based on other kinds of chemistry and they may multiply on Venus or Jupiter. At least we cannot prove at present that they do not. Even more interesting is the possibility that life on their planets may be in a more advanced stage of evolution. Present-day man is in a peculiar and probably temporary stage. His individual units retain a strong sense of personality. They are, in fact, still capable under favorable circumstances of leading individual lives. But man's societies are already sufficiently developed to have enormously more power and effectiveness than the individuals have. It is not likely that this transitional situation will continue very long on the evolutionary time scale. Fifty thousand years from now man's societies may have become so close-knit that the individuals retain no sense of separate personality. Then little distinction will remain between the organic parts of the multiple organism and the inorganic parts (machines) that have been constructed by it. A million years further on man and his machines may have merged as closely as the muscles of the human body and the nerve cells that set them in motion. The explorers of space should be prepared for some such situation. If they arrive on a foreign planet that has reached an advanced stage (and this is by no means impossible), they may find it being inhabited by a single large organism composed of many closely cooperating units. The units may be "secondary" — machines created millions of years ago by a previous form of life and given the will and ability to survive and reproduce. They may be built entirely of metals and other durable materials, if this is the case, they may be much more tolerant of their environment multiplying under conditions that would destroy immediately any organism made of carbon compound and dependent on the familiar carbon cycle. Such creatures might be relics of a past age, many millions of years ago, when their planet was favorable to the origin of life or they might be immigrants from a favored planet.

单选题 What does the word "cheer" (Para. 1, Line 2) imply?

单选题 Humans on Earth are characterized by______.

【正确答案】 A

【答案解析】解析：推理题。本题可用排除法。根据第二段中“They are，in fact，still capable under favorable circumstances of leading individual lives”可知选项B与原文不符；由第二段最后一句话可知，人类社会拥有强大的力量和效率而非人类自己，故排除C项；从第二段第二行“…a strongsense of personality”可知，人类有很强的个人意识，排除D项。故答案为A。

单选题 According to this passage, some people believe that eventually______.

单选题 Even most imaginative people have to admit that______.

【正确答案】 B

【答案解析】解析：推理题。本题可用排除法。A项：人类社会和其他星球上的社会一样先进。文中并没有这样说，只是假设其他星球也许比地球上的社会更先进，故排除；C项：人们很难去区分人体的有机部分和无机部分。而文章的第三段明确表明，这两者之间有些许的不同，故排除；D项：有机体比机器更富创造力。在原文中并未体现，也可排除。故答案为B。