1. 语法填空

    The Earth is a planet. It and seven other planets go  the Sun. We  (call)the eight planets and the Sun the solar system.  first planet, next to the Sun, is Mercury(水星). It is 58 million  (kilometer)from the Sun. Venus(金星)is the second planet from the Sun, and  (we)planet, the Earth, is the third. It is 150 million kilometers from the Sun.

    Jupiter(木星), Saturn(土星), Neptune(海王星)and Uranus(天王星)are all  (big)than the Earth,   Venus, Mars and Mercury are smaller than the Earth.

    Animals, trees and humans can only live  the Earth-the other planets in our solar system do not have air  water. Do any planets in other solar systems have  (life)? We don't know about it.