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How could I use has/have with passive.

For example,

This has already proofed in 1990.

or

This has already been proofed in 1990.

Which one is correct?

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  • "This has already been proven." or "This was already proven in 1990". We don't use specific time phrases like "in 1990" with Present Perfect. Commented Jan 8, 2019 at 10:09
  • @CowperKettle Thanks a lot. Could you please post it as an answer, this will be very helpful.
    – Maryam
    Commented Jan 8, 2019 at 10:18

1 Answer 1

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"This has already been proven." or "This was already proven in 1990". We don't use specific time phrases like "in 1990" with Present Perfect.

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