I' I would\/could\/should\/had. I would\/could\/should\/had. Generally would be used the most.
1, would be pronounced as [w?d] It means: willing, will, will, will, plan, probably. Also the past tense of will.
2. could be read as [k?d] The past tense of can, can, intends, is used in the hypothetical conditional, and also in the subjunctive conclusion.
3, should be pronounced as [??d], Meaning: should, will, could, should have. It shall also be past tense.
4, had is pronounced [h?d], meaning: have (past tense and past participle); To receive, take, or buy.
There are usually the following:
①I'd=I would, which means I would. This is also the most commonly used.
②I'd=I could, which means I could.
③I'd=I should, which means I might, I should.
④I'd=I had, which means I have, I accept, etc.