Second, 1. No one has found any life 2. We have sent them three letters. But she was never four years old. I saw him show foreign tourists around.

Third, read1.in1961.2. It sent the first space station into space. 3. A space station. 4. Until1the late 1980s. 5. The history of the space station and what life was like in the space station.

Four. 1.C2 B3 . a4 . D5 . B6 . C7 . A8 . C9 . b 10 . a

Fifth, scientists believe that there have been millions of years of life on the earth. The other seven planets revolve around the sun like the earth. None of them has an environment like the earth. So scientists don't think they will find life on it. The sun and its planets are called the solar system. Our solar system is a small part of a large group of stars and planets. We call it the Milky Way. Scientists have also discovered many other galaxies in the universe. So it is impossible to imagine how big the universe is. We always ask such a question: Are we alone with so many stars in the universe? Is there life in space? We are looking forward to knowing the answer.