根据学过的课文，判断正（T）误（F）
The Earth is a planet and it goes around the Sun．Seven other planets also go around the Sun．None of them has an environment with air，so people and things cannot grow．The Sun and its planets are called the solar system．The solar system is a small part of our galaxy．
The stars we see at night are the suns in other solar systems．There are more than 200 billion stars in our galaxy，called the Milky Way，and our Sun is only one of them．
But scientists have discovered many other galaxies in the universe．They are a long way away and their light has travelled for many years to reach us．It is hard to understand how large the universe is．
Scientists have sent lots of spacecraft to look at other planets in our solar system，and some spacecraft have gong beyond the solar system．However，no one has discovered any life in space yet．
But why has no one from other planets sent us a message？Have they tried to send information to us？With so many stars in the universe，are we alone，or is there life out there in space？We don’t know．．．yet．
小题1:The Sun is one of the Earth planets．
小题2:There is more than one galaxy in our solar system．
小题3:．There are more than 200 billion stars in the Milky Way．
小题4:．Scientists have found life on other planets．
小题5:They’ve received no messages from space．