1、I forgot to ask him for his address.

　　我忘記向他要地址。

　　2、 I forgot my purse (= I did not remember to bring it) .

　　我忘了帶錢包。

　　3、‘Hey, don't forget me (= don't leave without me) !’

　　“喂，走時別落下我！”

　　4、Aren't you forgetting something? (= I think you have forgotten to do sth)

　　你是不是忘了什么？