Scientists think that there has been life for__31_ of years. However we haven’t found life on other planets _32_ . The earth is a planet and it _33__ around the sun. Seven other planets also go _34_ the sun. The sun and its planets are __35  the solar system. The solar system is a small part of our galaxy.
Scientists __36_ lots of spacecraft to look at other planets in the solar system, and some spacecraft have gone __37_ the solar system. However, no one __38_ any life in space yet.
But why has no one from other planets sent us a message ? Have they tried to send _39_ to us ? _40_so many stars in the universe, are we alone, or is there life out there in space ? We don’t know.

Scientists think that there has been life for__31_ of years. However we haven’t found life on other planets _32_ . The earth is a planet and it _33__ around the sun. Seven other planets also go _34_ the sun. The sun and its planets are __35  the solar system. The solar system is a small part of our galaxy.

Scientists __36_ lots of spacecraft to look at other planets in the solar system, and some spacecraft have gone __37_ the solar system. However, no one __38_ any life in space yet.

But why has no one from other planets sent us a message ? Have they tried to send _39_ to us ? _40_so many stars in the universe, are we alone, or is there life out there in space ? We don’t know.

Scientists think that there has been life on Earth for   【小题1】 (百万) of years. However, we haven’t found life on other   【小题2】  (行星) yet. The earth, the moon, and the sun are a small part of our galaxy. Scientists have   【小题3】  ( 发现) many other galaxies in the universe. And there are many books about the universe. I’ve just finished   【小题4】 (看) a great book at school. It is a book about the solar system. It is so good that I’ve 【小题5】   (已经) asked the library to keep the next book for 【小题6】 (我). In the book, it says that astronauts have    【小题7】  (去) to Mars and even to Jupiter. I’ve never read that before. I’ve  【小题8】 (写信) to NASA to ask them for  【小题9】 （更多）information about astronauts and space. I hope they will write    【小题10】  (回) soon.