The contraction is spelled shouldn't.
The correct spelling of the contraction is should've.
Both "it is" and "it has" use the same contraction, it's(with an apostrophe).If the context does not make the tense clear, it should be written out.
aren't
won't
The contraction form of who is is who's.Example: Who's at the door?
The contraction is spelled "doesn't." The past tense is didn't.
contact
haven't
you're
I've
They're
QTR.