1、区别:三个单词的区别在于不同时态和不同人称之间,三个单词其实表达为一个意思。
2、用法:
如果是一般现在时:第三人称单数的时候用has,其它(如第一人称和第二人称)用have。
如果是一般过去时:全部都用had
3、拓展:have been,has been, had been
(1)解释:have/has/had+been 都是完成时。
(2)区别:has/have been是现在完成时,has用于第三人称单数; had been过去完成时,跟前者相比,比前者更为过去;
(3)例句:
He has been doing this work for a period of time.
I want to have this book.
Have you pass the math exam?
Do you ever had a thought that you can win this game?