复习目标：1.Words and useful expressions in this unit .
2. Talk about how long you have been doing things .
重难点：现在完成进行时。
一.课前预习：
Read through this unit and finish these exercises :
Task 1. Words and useful phrases in this unit :
1 收集_________2 自…以来_________ 3 筹集 ________4 几个的 ________
5 邮票_________ 6 风筝__________ 7 储存 ________ 8 收集者 ________
