Ex 2
2 It is important to send rockets into space.
3 The Earth revolves around the Sun in other orbit, earth is a planet in the solar system.
4 The idea of human life on Mars far -fetched.
5 We have obtained a lot of knowledge about the solar system in recent years.
6 The Earth rotates around the Sun every 365 days.
7 My knowledge of space is very limited. I'd like to know more about it.
8 The Moon is a satellite of the Earth.