Just wondering if these are considered vaild contractions in the English language.
Double Contractions, like shouldn’t’ve (should not have), couldn’t’ve (could not have), etc.
I heard this while watching a Lee Marvin/ Charles Bronsen movie the other day, “I’d stop now if I thought the killing’ld stop”. Its the “killing’ld” (killing would) that intrigued me.
Thanks.
Sure, I’ve’nt any idea why they wouldn’t’ve been OK.
Sorry, couldn’t resist. 
Number 1 is definitely acceptable, although use of such contractions is limited to informal speech or writing.
Number 2 is a grey area. Contractions tend to be pronouns paired with forms of be (she’d), or negatives of be (won’t). There are exceptions to this rule (O’clock, Hallowe’en), however these tend to be archaic. So that comes back to it being a judgement call on your part. Who is your audience? What level of formality is expected? etc.
A general rule of thumb is that–in writing–a conservative style uses NO contractions and an informal style uses them sparingly.
However, when it comes to informal conversational speech, pretty much anything that would be widely understood and easily deconstructed is fair game. You understood what he meant when he said “killing’ld”, yes? Then it’s a word–although probably not one you’d want to use in your doctoral thesis…
bella