I'd=i would 也可以是i'd=i had?

I'd=i would 也可以是i'd=i had? 怎么区分I’d 是I had 还是I would I’d 是I would fail?还是I had fail? i'd rather 的'd是 had还是would I'd like=I would I'd bettle hit the books!这句话中的I'd 是I had I would还是 I should? I'd like you to do me a favor这里i'd 是i would 还是i had i'd better是i had better还是i would better I'd 如何区分是I could还是I would? I'd 是指I could 还是I would? I wish I ____ a million today.a.have B.had C.had had D.would "i hope she'd be very happy".这里的" 'd " 是had还是would?为什么?