As space science develops, man has learned more and more about space. Space is not only 【小题1】 but also dangerous. While working in space, spacemen are facing danger as well as success.

Scientists have 【小题2】 out that the radiation (辐射) is the greatest danger to spacemen. When 【小题3】 are working in space, they are in danger of the radiation from the sun and other stars, which is bad for their health.

Space 【小题4】 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 【小题5】 , and the rest are space rubbish. A small 【小题6】 of rubbish even knocks a spaceship window and 【小题7】 some damage (损坏).

Scientist are watching and reporting any possible danger all the time. They are working to deal 【小题8】 space rubbish. 【小题9】 space is really dangerous, it interests many people on the earth. In the near future, it may become 【小题10】 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 improve the space environment.

We live on the planet（星球）Earth. Could we live on a 【小题1】 planet? To find out, scientists have been studying Mars for a long time. They 【小题2】 special machines to Mars. These machines are called rovers.

Scientists on Earth tell rovers what to do. Talking to rovers is something like playing a computer game. From Earth scientists can 【小题3】 what rovers are doing. Rovers usually move along the surface of Mars. They take pictures, study the planet and send the 【小题4】 back to Earth. They help us learn many things about Mars.

The moon 【小题1】 around the earth. It is quite near to us in 【小题2】. It is only 380,000 kilometres away and man has 【小题3】 visited it. So far, no man has travelled 【小题4】 than the moon, but spaceships without people have 【小题5】 other planets of the universe.

Many countries have 【小题6】 up satellites(卫星) into space.

These satellites go 【小题7】 the earth and help us to learn more about the earth, the weather and other things. Many countries use these satellites to send and receive 【小题8】. For example, 【小题9】 their help, China can send its TV and radio programmes to other countries. We can also use satellites to 【小题10】 us make telephone calls to foreign countries.