過去完成時：用法：在過去的時間里，兩個動作中，發生在前的哪個動作要用過去完成時。

　　結構：had+過去分詞

　　After she had finished her homework, she went shopping.

　　They had sold the car before I asked the price.

　　The train had left before I arrived at the station.

　　After/before引導的時間狀語從句放在句首要在句子后面加逗號，如果放在主句后則不用加。

　　1.變疑問句將助動詞移到句首

　　Had she finished her homework?

　　2.變否定句在助動詞后面加not

　　She hadn’t finished her homework.

　　3.肯定回答及否定回答

　　Yes, she had. No, she hadn’t.

　　4.特殊疑問句：

　　What had she done?