點擊查看：2017年12月大學英語六級考試閱讀理解100篇

　　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 U.S.had acquired when it purchased Louisiana,and the Apollo 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 science simply by going where no scientists had gone before.

　　Today Mars looms as humanity's next great terra incognita(未探明之地).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 in vites a couple of others:Are there experiments that only human could do on Mars?Couldthose experiments provide 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 thatthe Red Planet once had abundant stable,liquid water and by the continuing controversy over suggestions the bacterial fossils rode to Earth on a meteorite(隕石)from Mars.A mor 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.

　　1.For What purposes did the explorers go the unknown places in the past?

　　2.In the exploration of Mars,_______________________still remains uncertain.

　　3.What has long been regarded as unimportant in the past explorations?

　　4.What has been found on a meteorite from Mars?

　　5.The conditions under which life originates would be revealed with the proof of_________________on Mars.

　　答案：

　　1.[For economic and nationalistic purposes.]

　　[定位]根據(jù)explorers go to unknown查找到全文首句。

　　解析：首句中提到，幾個世紀以來，出于或多或少的經(jīng)濟原因及國家主義原因，探險家冒著生命危險深人到未知領域。本題是詢問原因，所以reasons的定語從句中的內(nèi)容即為答案For economic and nationalistic purposes。

　　2.[the prospects for a short-term financial return]

　　[定位]根據(jù)Mars，uncertain查找到第3段前兩句。

　　解析：第3段第2句提到，探索火星在短期內(nèi)未必能有經(jīng)濟回報。題干中的uncertain對應原文中的doubtful，因此本題答案為the prospects for a short-term tinancial return。

　　3.[Science.]

　　[定位]根據(jù)has long和exploration查找到第3段第3句。

　　解析：原文該句提到，在以往探險中一直扮演次要角色的科學這一次終于注定是主角了嗎?說明在以往探險中，一直被認為不重要的就是科學，題干中的unimportant對應原文中的a minor role，所以答案為Science.

　　4.[Bacterial fossils.]

　　[定位]根據(jù)on a meteorite from Mars查找到末段第2句。

　　解析：末段第2句中suggestions后的內(nèi)容表明從火星落到地球上的隕石里含有細菌化石，所以本題答案為Bacterial fossils.

　　5.[life]

　　[定位]根據(jù)conditions under which查找到末段倒數(shù)第2句。

　　解析：原文結構比較復雜，分析其句子結構后可知，火星上生命存程的證據(jù)可使研究者了解在何種條件下生命會出現(xiàn)，也就是說，在何種條件下生命會出現(xiàn)可以通過火星上生命存在的證據(jù)顯示出來。因此答案為life。

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