The earth is a        (行星)and it goes around the sun. Seven others also go around the sun.        (没有一个)of them has an        (环境)like that of the        (地球), so scientists do not think they will find life on them. The sun and its planet are called the        (太阳的)system, and ours is a small part of a much larger         (群, 组)of stars and planets, called the        (星系).

    Scientists have also        (发现)many others in the        (宇宙). They are very far away and their        (光)has to travel for many years to reach us. So how large is it? It is impossible to imagine.

Simon was interested in             when he was young.

I don't know how                    information on the Internet.

Mars                     from our earth.

So       , the Chinese government has        on people's health care.

The students       .

    I always believed in UFOs, but I didn't see one. My husband didn't believe in UFOs before that 1.

    Last Friday night, he drove home 2 work. He drove near a gas station (加油站) when he saw a bright light. It looked 3 a light. It was low, and it wasn't moving. He didn't 4 too much about it. He thought maybe it was a street light, so he 5 up farther and then the light went off. But a few minutes later, it was on. He stopped the car. He 6 and looked around, but saw nothing.

    After a short while the 7 was on again. He got on the car and drove another 2 miles to our house. He sat in the 8 for a few minutes thinking of what he saw. He got out of the car and the moving light went off. Then when he looked back, he could 9 it in the sky. Then he was 10 it must be a UFO. He went into our house and told me about it.

    Sally Ride was born in California in 1951. She was the first American woman to travel into space. She loved to play tennis and wanted to be a tennis player when she was young. But after three months' professional（专业的）training, she changed her mind. She went to Stanford University and started to study science. She studied stars and planets. She did researches at the university and got her PhD in astrophysics（天体物理学博士学位）after several years' hard work.

    In 1977, she took a test to become an astronaut. And then she was picked up from over 8, 000 people. In order to realize her dream of going into space, she had to get different kinds of special and difficult training. She learned how to fly a plane, how to jump out of a plane as well as how to operate（操作）special machines.

    Sally and four other astronauts flew a spaceship called Challenger on Jun. 18, 1983. She became the first American woman to travel into space. Later, she taught at the University of California. Then she wrote seven books on space for children, encouraging children to study science. Unfortunately, she died in 2012.