复习目标：
１．Words and useful expressions in this unit.
2. Talk about past events .
重难点: 过去进行时
一．课前预习：
Read through this unit and finish these exercises :
Task 1. Words in this unit :
1 外星人__________ 2 当…时候 ___________ 3 经历__________ 4 想象________ 5 跟随 ________ 6 令人惊异的____________ 7 发生_____________
8 事故_________ 9 现代化的__________ 10 意思 ____________11 buy(Vp.)_______
