[Grammar] "Didn't you know" or "Did you not know"

[shimacatu_sa]

Hi,
I am wondering about the following sets of phrases.
Is each set of the phrases mostly interchangeable?

I assume the tones and contexts matter, but the B form sounds more formal or more forceful to me. Is it more natural/appropriate to use the A form in everyday conversation? I have personally never used the B form.

A. Didn't you know about his problem?
B. Did you not know about his problem?

A. How didn't I know it?
B. How did I not know it?

A. Aren't you clear with this subject?
B. Are you not clear with this subject?

A. Wasn't he your friend too?
B. Was he not your friend too?

A. Haven't I paid you yet?
B. Have I not paid you yet?

Thank you.

 

[Rover_KE]

The B forms are formal as the standard advice is not to use contractions in formal writing.

The A forms are more likely to be used in everyday conversation.

 

[Skrej]

I'm more likely to choose the B forms if I really want to verbally stress the 'not' for theatrical effect.

 

[jutfrank]

I'd say both forms are equally natural. The B forms have slightly more focus on the negativity of the verb/adjective/noun. They are not necessarily more formal when used in this way.