have、had的用法

作「主動詞」時, 意為: 有,使,...等十幾種意思(字典有).
現在的事實或狀態用have; 過去的事實或狀態用had
I have a dog. ~~~ I had a dog last year.
I have my car repaired. ~~~ I had my car repaired yesterday.

作「助動詞」時, have/had 本身無意義.
- 現在完成式 have + p.p.
- 過去完成式 had + p.p.
- 未來完成式 shall/will have + p.p.
- 假設語氣與過去事實相反: If + S + had + p.p., S + would/should/could/might have + p.p.

作「主動詞」時的完成式, 同助動詞用法, 惟p.p.= had:
現在完成式 have had; has had
過去完成式 had had
未來完成式 will/shall have had