The main contractions are these:
a) Auxiliary verbs
The verb 'to be' contracts like this:
I'm, you're, he's, she's, it's, we're, they're.
The verb 'to have' contracts like this:
I've, you've, he's, she's, it's, we've, they've.
There is also " 'd ", which can be both 'had' and 'would'.
isn't, aren't, doesn't, don't, didn't, hadn't, won't, wouldn't, can't, couldn't, mustn't