1、I'd 后面如果是动词原形，说明是I would 的缩写，意思是：我将。
There are some questions I'd like to ask .
有些问题我想问一下。
2、I'd 后面如果是动词的过去分词形式，说明是I had 的缩写，意思是我已经。
I felt absolutely certain that I'd seen her before.
我完全确信自己以前曾见过她。
短语用法：
1、II'd like = I would like我想要做什么。
She asked me what I would like to do and mentioned a particular job .
她问我想干什么，然后提到了一份工作。
2、I'd better = I had better 我最好干什么。
I worried for ages and decided that I had better break it to her.
我烦恼了很长时间，后来决定还是把这事告诉她。
