拓展：have been，has been， had been

　　1.解釋?zhuān)篽ave/has/had+been 都是完成時(shí)。

　　2.區別：has/have been是現在完成時(shí),has用于第三人稱(chēng)單數; had been過(guò)去完成時(shí),跟前者相比,比前者更為過(guò)去;

　　3.例句：

　�。�1）He has been doing this work for a period of time.

　�。�2）I want to have this book.

　�。�3）Have you pass the math exam?

　�。�4）Do you ever had a thought that you can win this game?