大学英语综合教程2第三版课后习题答案

一、 1. D 2. C 3. A 5. B
二、 1. No one has discovered any life 2. we have already sent them 3. but she has never been 4. I saw him showing the foreignvisitors around
三、1. In 1961. 2. It sent the first space station intospace. 3. A space station. 4. Until the late 1980s. 5. The history of space stations and whatthe life in space stations is like.
四、 1. C 2. B 3. A 4. D 5. B 6. C 7. A 8. C 9. B 10. A
五、Scientists thinkthat there has been life on earth for hundreds of millions of years. Sevenother planets go around the sun like the earth. However, none of them has anenvironment like that of the earth. So scientists do not think they will findlife on them. The sun and its planetsare called the solar system. And our solar system is a small part of a muchlarger group of stars and planets. We call it Galaxy. Scientists have alsodiscovered many other galaxies in the universe. So it is impossible to imaginehow large the universe is. We havealways asked the question: With so many stars in the universe, are we alone? Isthere life out there in the space? We’re looking forward to know the answer.