Question

We had completed our task guess proper tense
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Answer 1

Answer:

As far as I understand meaning of Past Perfect tense, I think it makes sense when you have some more information in the sentence about something that happened later, example:

I had completed all the tasks before John came back.

(John came back in the past, but I had completed the tasks earlier)

Answer 2

It is in past perfect tense..

It's structure is ( S+had + v3 + object )

hope it helps to you..