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  3. For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic an

For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic an

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问题      For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic and nationalistic. Columbus went west to look for better trade routes to the Orient and to promote the greater glory of Spain. Lewis and Clark journeyed into the American wilderness to find out what the US had acquired when it purchased Louisiana, and the Appolo astronauts rocketed to the moon in a dramatic show of technological muscle during the cold war.
     Although their missions blended commercial and political-military imperatives, the explorers involved all accomplished some significant science simply by going where no scientists had gone.
     Today Mars looms as humanity’s next great terra incognita. And with doubtful prospects for a short- term financial return, with the cold war a rapidly fading memory and amid a growing emphasis on international cooperation in large space ventures, it is-clear that imperatives other than profits or nationalism will have to compel human beings to leave their tracks on the planet’s reddish surface. Could it be that science. which has long played a minor role in exploration, is at last destined to take a leading role? The question naturally invites a couple of others: Are there experiments that only humans could do on Mars? Could those experiments pro- vide insights profound enough to justify the expense of sending people across interplanetary space?
     With Mars the scientific stakes are arguably higher than they have ever been. The issue of whether life ever existed on the planet, and whether it persists to this day, has been highlighted by mounting evidence that the Red Planet had abundant stable, liquid water and by the continuing controversy over suggestions that bacterial fossils rode to Earth on a meteorite from Mars. A more conclusive answer about life on Mars, past or present, would give researchers invaluable data about the range of conditions under which a planet can generate the complex chemistry that leads to life, If it could be established that life arose independently on Mars and Earth, the finding would provide the first concrete clues in one of the deepest mysteries in all of science: the prevalence of life in the universe.  
     45 The passage tells us that proof of life on Mars would ______.
选项 A、make clear the complex chemistry in the development of life
B、confirm the suggestion that bacterial fossils travelled to Earth on a meteorite
C、reveal the kind of conditions under which life originates
D、provide an explanation why life is common in the universe
答案D
解析 细节题。最后一句指出；如能证明生命独立存在于火星与地球上，这一发现将给科学中最深奥秘之一的“宇宙中生命普遍存在”问题提供第一个具体线索，即可解释为何生命在宇宙中普遍存在。
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