Unit 4 Amazing Science Welcome to the unit Topic 3 I dont think aliens can be found in space. Section C New words solar 太阳系太阳系 Roman 古罗马的,罗马帝国的古罗马的,罗马帝国的 diameter 直径直径 storm 风暴,暴雨风暴,暴雨 gravity 重力,引力,地心引力重力,引力,地心引力 limit 限制,限定限制,限定 Teaching aims and demands 1. Learn the new words and expressions: storm, search, dry, base on Its diameter is 53% as long as that of the earth. 2. Review the passive voice. 3. Learn something more about Mars. 1.the fourth planet from the sun 2.the Red Planetthe rocks,