have has had是怎么回事,什么样子时在用什么?is are（was,were）呢?

have 是动词原形用于一般现在时.I have a book
has是动词的单数第三人称形式用于主语是第三人称的一般现在时 He has a book.
had是动词have的过去式用于一般过去时.He had an exam yesterday.其他的会吗会is 用于主语是第三人称的一般现在时或现在进行时。如 He is tall .He is talking with a friend.are用于主语是第二人称或各种人称的复数。如You are a student . We arehappy . The students are playing on the playground.was是 is ,am的过去式用于一，三人称的单数的过去时中。如He was ill yesterday. I was at home yesterday. were是are 的复数用于第二人称和各种人称的复数形式。用于过去时we were tired . My books were on the desk just now.