Today's solar system, regarding the Earth as the life cradle，regarding Mars as the case example, regarding Jupiter as the eldest brother, regarding Saturn as the beautiful...

　　Congratulate you living in the solar system the third planet－is on the earth.We have so good environment, should like good cherish, and don't let the

　　Earth become the second "Mars"．

　　1．galaxy n．　　　　 星系，星群

　　2．illuminate vt. 使明亮，照亮

　　3．reserve vt. 储存，保存

　　4．ruthlessness n. 残忍，无情

　　5．humidity n. 谦虚，谦让

　　6．confirm vt. 确定，证实

　　7．cradle n. 发源地

　　1．How many planets are suitable for life's existence?

　　________________________________________________________________

　　________________________________________________________________

　　2．Why do other planets have no life?

　　________________________________________________________________

　　________________________________________________________________

　　【答案】　1.Only one.

　　2．Because the temperature on them is too high or too low.

　　Section Ⅰ　Warming Up & Reading－Preparing