Can you elaborate on this: You couldn't've known it

[Serzige]

Hi folks...
Can you elaborate on this: "you couldn't've known it". So, I am quite sure that in the written part it is not ok, nevertheless, I've heard people saying it...Then, is that ok when pronouncing it?

Thanks a lot!

[Yankee]

.
couldn't've
shouldn't've
wouldn't've
won't've
...
You're right, Serzige. Contractions such as the ones above are all quite normal in spoken English.

Amy