Why should mankind explore space? Why should money, time and effort be spent exploring and researching something with so few apparent benefits? Why should resources be spent on space rather than on conditions and people on Earth? These are questions that, understandably, are very often asked．
Perhaps the best answer lies in our genetic makeup（基因构成） as human beings．What drove our ancestors to move from the trees into the plains, and on into all possible areas and environments? The wider the spread of' a species, the better its chance of' survival． Perhaps the best reason for exploring space is this genetic tendency to expand wherever possible． Nearly every successful civilization has explored, because by doing so, any dangers in surrounding areas can be identified and prepared for． Without knowledge, we may be completely destroyed by the danger． With knowledge, we can lessen its effects．
Exploration also allows minerals and other potential（潜在的） resources to be found．Even if' we have no immediate need of them, they will perhaps be useful later． Resources may be more than physical possessions． Knowledge or techniques have been acquired through exploration．The techniques may have medical applications which can improve the length or quality of our lives．We have already benefited from other spin-offs including improvements in earthquake prediction, in satellites for weather forecasting and in communications systems． Even non-stick pans and mirrored sunglasses are by-products （副产品） of technological developments in the space．
While many resources are spent on what seems a small return, the exploration of' space us．While space may hold many wonders and explanations of how the universe was formed or how it works, it also holds dangers． The danger exists, but knowledge can help human being to survive． Without the ability to reach out across space, the chance to save ourselves might not exist．
While Earth is the only planet known to support life, surely the adaptive ability of humans would allow us to live on other planets． It is true that the lifestyle would be different, but human life and cultures have adapted in the past and surely could in the future．
Why does the author mention the questions in Paragraphl ?

A．To express his doubts．

B．To introduce points for discussion．

C．To compare different ideas．

D．To describe the conditions on Earth．

What is the reason for exploring space based on Paragraph2 ?

A．Humans are nature-born to do so．

B．Humans have the tendency to fight．

C．Humans may find new sources of food．

D．Humans don't like to stay in the same place．

The underlined word “spin-offs” in Paragraph 3 probably refers to       ．

A．survival chances	B．potential resources
C．unexpected benefits	D．physical possessions

What makes it possible for humans to live on other planets'?

A．Our genetic makeup．	B．The adaptive ability of' humans．
C．Resources on the earth．	D．By-products in space exploration．

Which of the following statements can best sum up the passage'?

A．Space exploration has created many wonders．

B．Space exploration provided the best value for money．

C．Space exploration can benefit science and technology．

D．Space exploration may help us avoid potential problems on Earth．