题目内容：

As space science develops, man has learned more and more about space. Space is not only a1. but also dangerous. While working in space, spacemen are facing danger as well as s2..

Scientists have found out that the in radiation(辐射)is the greatest danger to spacemen. When spacemen are working in space, they are in d3. of the radiation from the sun and other stars, which is bad for their health. The h4. of the radiation won’t be found until their children even grandchildren are born. Some s5. medicine may work a little, but no really effective medicine has been found so far.

Space r6. is also thought to be a great danger to spacemen. It’s reported that there were 9,000 man-made things flying in space. About 30% of these are satellites, 10% are s7., and the rest are space rubbish. An explosion(爆炸)in space in 1999 made a cloud of 300,000 fragments (碎片), each at least 4mm in size. A small piece of these even knocked a spaceship window and c8. some damage（损 坏）.

Scientists are watching and reporting any possible danger all the time. They are working to deal with space rubbish. A9. space is really dangerous, it interests many people on the Earth. In the near future, it may become possible for people to spend a few days in a space hotel. We may even choose to leave the earth and live in space in a few years. So we should do something to help i10. the space environment.