[Grammar] I think we have/had/x met before.

[kadioguy]

a. I think we have met before.
b. I think we had met before.
c. I think we met before.
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Are all of them acceptable? What is the difference in meaning between them? Could you tell me?

 

[jutfrank]

a. before now
b. before a point in the past

You don't need to use c.

 

[kadioguy]

You don't need to use c.

How about this? Is it better?

I think we met yesterday/last week/ten days ago ... etc.

 

[jutfrank]

How about this? Is it better?

I think we met yesterday/last week/ten days ago ... etc.

Yes, that's correct.