题目内容
Space is dangerous place, not only because of meteors(流星) but also because of rays from the sun and other stars. The atmosphere again acts as our protective blanket on earth. Light gets through, and this is essential for plants to make the food which we eat. Heat, too, makes our environment endurable. Various kinds of rays come through the air from outer space, but enormous quantities of radiation(辐射) from the sun are screened off. As soon as men leave the atmosphere they are exposed to this radiation but their spacesuits or the walls of their spacecraft, if they are inside, do prevent a lot of radiation damage.
Radiation is the greatest known danger to explorers in space. The unit of radiation is called “rem”. Scientists have recon to think that a man can put up with far more radiation than 0.1 rem without being damaged; the figure of 60 rems has been agreed on. The trouble is that it is extremely difficult to be sure about radiation damage--a person may feel perfectly well, but the cells of his or her sex organs may be damaged, and this will not be discovered until the birth of deformed(畸形的) children or even grandchildren.
Missions of the Apollo flights have had to cross belts of high amount of rems. So far, no dangerous amounts of radiation have been reported, but the Apollo missions have been quite short. We simply do not know yet how men are going to get on when they spend weeks and months outside the protection of the atmosphere, working in a space laboratory. Drugs might help to decrease the damage done by radiation, but no really effective ones have been found so far.
1.According to the first paragraph, the atmosphere is essential to man because .
A.it protects him against the harmful rays from space
B.it provides sufficient light for plant growth
C.it supplies the heat necessary for human survival
D.it screens off the falling meteors
2.The harm radiation has done to the Apollo crew members .
A.is insignificant B.seems overestimated
C.is enormous D.remains unknown
3.It can be inferred from the passage that .
A.the Apollo mission was very successful
B.protection against space radiation is no easy job
C.astronauts will have deformed children or grandchildren
D.radiation is not a threat to well-protected space explorers
4.The best title for this passage would be .
A.The Atmosphere and Our Environment B.Research on Radiation
C.Effects of Space Radiation D.Importance of Protection Against Radiation
ADBC
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 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 industry!
While many resources are spent on what seems a small return, the exploration of space allows creative, brave and intelligent members of our species to focus on what may serve to save 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 beings 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.
【小题1】Why does the author mention the questions in Paragraph1?
A.To express his doubts. | B.To compare different ideas. |
C.To introduce points for discussion. | D.To describe the conditions on Earth. |
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. |
A.survival chances | B.potential resources |
C.unexpected benefits | D.physical possessions |
A.O ur genetic makeup. | B.Resources on the earth.. |
C.The adaptive ability of humans. | D.By-products in space exploration. |
A.Space exploration has created many wonders. |
B.Space exploration provides the best value for money. |
C.Space exploration can benefit science and technology |
D.Space exploration may help us avoid potential problems on Earth. |