求问have has had的用法~谢谢~

has 单数第三人称用,如He has a book.She has a house.It has a tail.
have 其余人称用这个
had 是以上两个的过去式,用于所有人称,表示过去曾经“有”.
如,He had a house last year.过去式用于所有人称：he had a new car and a boat. 他拥有新车和游艇。in 1989 the party had 10,000 members.1989年该党有10,000名党员。I went to a few parties and had a good time.我去参加了几个派对，玩得很开心。he had a look round.他四下看了看。 have, has, had 构成现在完成时和过去完成时的肯定句、疑问句和否定句。现在完成时：肯定句：He has finished the paper. 他读完了报纸。/ I have finished the paper. 疑问句：Has he finished the paper?否定句：He has not finished the paper. 过去完成时：肯定句：He had finished the paper before he did the homework.疑问句：Had he finished the paper before he did the homework?否定句：He had not finished the paper before he did the homework.he had asked her.他问过她了。she will have left by now.她现在应该已经离开了。I could have helped, had I known.当时我要是知道的话，我可能就帮忙了。‘Have you seen him?’ ‘Yes, I have.’.“你见到他了吗？”“见到了”。