to prove

[Unregistered]

I am having trouble remembering the conjugation rules for the verb "to prove", e.g. does one say, "It has been proved" or "It has been proven?" Also, is it correct to say, "I have proved that more than once" or "I have proven that more than once?"

[Anglika]

They have about equal use.

Also, is it correct to say, "I have proved that more than once" or "I have proven that more than once?" Both are fine

[njwise]

This is so interesting because I remember once in a journalism class, I received an F on a paper for misusing "proven" somehow. Have the rules changed over the last 30 years?