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【单选题】

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 U.S. 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 by going where no scientists had gone before.
Today Mars looms (隐约出的) as humanity’s next great terra incognita (未控明之地). 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 suce. 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 human could do on Mars7 Could those experiments provide in- sights 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 once had abundant stable, liquid water and by the continuing controversy over suggestions the bacterial fossils rode to Earth on a meteorite (陨石) 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. According to the passage, the chief purpose of explorers in going to unknown places in the past was ()

A.
to display their country's military might
B.
to accomplish some significant science
C.
to find new areas for colonization
D.
to pursue commercial and state interests
题目标签:陨石
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【单选题】People once widely believed that intelligent life existed on Mars. The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence. The lines were thou...

A.
The meteorite containing organic compounds is part of Mars.
B.
A Martian rock struck Earth about 11,000 years ago.
C.
The organisms came back to life after the collision with Earth.
D.
The inhabiting organisms appeared more than three billion years ago.

【单选题】People once widely believed that intelligent life existed on Mars. The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence. The lines were thou...

A.
the minor geologic characteristics of Mars
B.
natural valleys on the surface of Mars
C.
rivers that have kept flowing since ancient times
D.
a system that irrigates the whole surface

【单选题】People once widely believed that intelligent life existed on Mars.The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence.The lines were though...

A.
Because the surface of Mars seemed to be geometric.
B.
Because the lines were drawn across the surface of the planet.
C.
Because a system of canals was thought to be there.
D.
Because it was the Martians that built the canals.

【单选题】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 t...

A.
To find out if life ever existed there.
B.
To see if humans could survive there.
C.
To prove the feasibility of large-scale space ventures.
D.
To show the leading role of science in space exploration.

【单选题】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 t...

A.
to display their country"s military might
B.
to accomplish some significant science
C.
to find new areas for colonization
D.
to pursue commercial and state interests