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 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? {{U}}With Mars the scientific stakes are
arguably higher than they have ever been{{/U}}. 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.
单选题
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
【正确答案】
D
【答案解析】细节题。答案信息见于文章第一句：...for reasons that were to varying degrees economic and nationalistic(因不同程度的经济与国别原因)。
单选题
At present, a probable inducement for countries to initiate large-scale
space ventures is ______.