Some people believe that humans could live on the planet Mars by the year 2100. Our own planet, the Earth, is becoming more and more c【小题1】 and polluted because of the increase in population. It is hoped that people could start to b【小题2】 a better world on Mars. Here is what life there could be like.

At present, our spaceship are too slow to carry large numbers of passengers to Mars-it would take months, with the development of t【小题3】, by the year 2100, the journey might only take about 20 minutes in spaceship that travel at the speed of light! However, the spaceship would travel so fast that the journey to Mars might be quite uncomfortable. Many people would f【小题4】 ill.

Humans cannot survive (活下来) without water, oxygen or f【小题5】. So far, nobody knows whether there would be enough water or oxygen on Mars for people there. Moreover, scientists are not sure whether plants could g【小题6】 on Mars. Food would most probably be in the form of pills (药丸) and would not be so tasty.

Gravity(重力) could be a【小题7】 problem. The gravity on Mars is only about three-eighths of that on the Earth. People would have to wear boots that are specially designed(设计) to stop themselves from floating(飘) off into space.

C【小题8】 with life on the Earth, life on Mars would be better in some ways. People would have more space. They might live in houses with huge comfortable rooms. What’s m【小题9】, robots would do most of their work so that they could have more time to relax. There would probably be no schools on Mars. Every student would have a computer at home connected to an interplanetary network, they would study at online schools with “e-teachers”.

Life on Mars would be i【小题10】 as well as challenging(有挑战性的).

Andy heard from his friend that a comet (彗星) was coming. He knew that a comet is a space rock. He wanted to watch it at 【小题1】 before sleeping.

When the evening came, it was a bit cold. So Andy 【小题2】 on a coat. He looked up in the sky. He could see the moon and some stars, but 【小题3】 new or special.

“Where is the comet? I only see the moon and some stars, ” he asked his friend on the phone. His friend told him where to look, 【小题4】 he still didn’t see it.

Andy went to wake his father up who was just 【小题5】 in the bedroom. Then Andy looked up in the sky 【小题6】 his father. Several minutes 【小题7】, they saw a fuzzy (模糊的) thing, which is bigger than a star. That was it.

“I think it would be like the moon or something, ” Andy said. “It's not big enough for that, and it might still be very 【小题8】 away from us,” his father said.

“I still wish I can see it better. ”

His father nodded and went inside. When he came back, he had a telescope(望远镜) in his hands. Through 【小题9】, they saw the comet a little better. It wasn’t much, but it helped.

After that night, Andy became interested in space and he thought being a(n) 【小题10】 must be cool! He wanted to go to the moon and even Mars on the spaceship one day.

Scientists think that 【小题1】 has been life on earth for 【小题2】 (million) of years. However, we haven’t found life on other planets yet. The earth is a planet and 【小题3】 goes around the sun. And there are seven other planets that also go around the sun. The sun and its planets are 【小题4】 (call) the solar system. The solar system is 【小题5】 small part of the universe.

Scientists have launched many spaceships to 【小题6】 [ɪkˈsplɔː(r)] other planets in the solar system. Some spaceships have gone 【小题7】 [bɪˈjɒnd] the solar system. However, no one 【小题8】 discovered any life in space yet.

Why has no one from other planets 【小题9】 ( send) us a message? Have they tried to send 【小题10】   (information) to us? With so many stars in space, are we alone, or is there life on other planets in space?