请问此句中的I'd 是would还是had?

I'd like to go by train.中的'd是would还是had I'd bettle hit the books!这句话中的I'd 是I had I would还是 I should? 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 better是i had better还是i would better "i hope she'd be very happy".这里的" 'd " 是had还是would?为什么? I'd like you to do me a favor这里i'd 是i would 还是i had 虚拟语气中'd怎么区别是had还是would? I'd=i would 也可以是i'd=i had? 请问句中的 there had never 是完成时态还是什么? I'd 如何区分是I could还是I would?