一、CDBCDBDCADDCAAB二、 1. Eight. 2. Theearth. 3. The galaxy. 4. It is too large to imagine. 三、 1. C 2. A 3. B 4. E

四、 1. There has been life 2. so wonderful that I have seen it 3. I don’t think there is life 4. has an environment like that 5. It’s impossibleto imagine