I had tested vs I have tested

[hampeh]

Dear teacher,


May I know what is the different between these sentences? Can I use both?


I had tested


&


I have tested

Thanks

 

[Mister Micawber]

.
This seems like deja vu.

I have tested is present perfect and indicates that the test was finished between some past point in time and now.

I had tested is past perfect and indicates that the test was finished between two points in past time. Past perfect normally requires mention of the more recent of those two points, so your sentence needs to be completed: I had tested the samples three times when your team took over.
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