As space science develops, man has learned more and more about space. Space is not only amazing but also dangerous. While working in space, spacemen are facing danger as well as success.
Scientists have found out that the radiation（辐射）is the greatest danger to spacemen in space. When spacemen are working in space, they are in danger of the radiation from the sun and other stars, which is bad for their health. The harm of the radiation won’t be found until their children even grandchildren are born. Some special medicine may work a little, but no really effective medicine has been found so far.
Space rubbish 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 spaceships, and the rest are space rubbish. An explosion（爆炸）in space in 1999 made a cloud of 300,000 fragments, each at least 4mm in size. A small piece of these even knocked a spaceship window and caused some damage(损坏).
Scientists are watching and reporting any possible danger all the time. They are working to deal with space rubbish. Although 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 improve the space environment.
. The writer mainly wants to tell his readers that the space is full of _____.

A．rubbish	B．danger
C．satellites	D．radiation

. How much does space rubbish take up of all the man-made flying objects?

A．30%

B．40%

C．50%

D．60%

Which of the following statements is true according to the passage?

A．Some children have been born in space.

B．People are not supposed to live in space.

C．Some people are eager to have a space trip.

D．No one is dealing with space rubbish now.

. The underlined word “fragments” in the third paragraph probably means _____.

A．broken pieces	B．flying dust
C．dangerous gases	D．space radiation

. What is the main purpose（目的）for writing the passage?

A．To ask people not to pollute the space environment.

B．To develop people’s interests in space travel in the future.

C．To tell readers what scientists are doing about space rubbish.

D．To tell people that space is dangerous and what the dangers are.