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WOULD YOU SAY "ONE OF YOUR FRIENDS" OR "ONE OF YOUR FRIEND" ?
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"One of your friends" would be the usual.
What sort of sentence did you want to write?

If you said "one of your friend", that would sound as if you were trying to say that your friend doesn't have a clone.
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The noun after "one of" is always plural. friends in this case.

I can't think of an exception.

CJ