how to use them
熱心網友
had been是過去的過去，也就是在過去某個時間之前就已發生的事情has/have been則是從現在時刻看已經完成的事情一般說來，當用前者時句中還應有另一表過去的謂語動詞或表過去的時間，如I had been 17 years old when I left high school.I had been 17 years old by this time of last year.
熱心網友
T o go to the bookshop to buy the book about the questions.
熱心網友
had been 表示過去完成的has/have been 表示現在完成的
熱心網友
had been 是has、havebean的過去形式啊，就是had是have/has的過去式。表示過去完成用had bean，表示現在完成用has/have bean