Past Perfect

[Casiopea]

Hello everyone,

Why can't I use in the following sentence the Past Perfect?

"What did you do before you came here?"

He came here in the past, and I want to know what he had done before that time.
Do you understand what I mean ?

Thanks in advance,
Dany

The simple tenses express a fact:

What do you do?
What did you do? <What was your job?>

The perfect aspect expresses a continuum of time, wherein two events are connected. The present perfect "have -ed" relates past time to the present, whereas the past perfect "had -ed" relates past time to past time.

In our example sentence, the clause "before you came here" refers to the past (before) and to the present (here), so present perfect would be best:

What have you done, since then and now.

What had you done, then in the past, not now at the present time.

[Dany]

The past perfect expresses an activity that was completed before another activity or time in the past.

Everyone had spoken by the time I arrived.
Everyone had spoken by 10 a.m.

If either before or after is used in the sentence, the past perfect is not necessary because the time relationship is already clear. The two sentences below have the same meaning and both are grammatically correct.

Sam left before Ann got there.
Sam had left before Ann got there.

Hope this helps.

Thanks for explanation

[aaa]

Welcome, aaa.

[Dandelion]

You're welcome, Dany.
Thanks, Casiopea.

[aaa]

Sorry, but I don't understand whether it is correct to use Past Perfect or not.

Please help me

It depends on situation you are in. In some cases it may be correct, in some - not quite. It depends on what exatcly you want to ask.

In general, Past Perf is not of very frequent use by native speakers. So, don't get your life complicated ;) Trust your teacher...

[Casiopea]

. . . , don't get your life complicated ;) Trust your teacher...

To be able to gerenate your own sentences, you need to know how the language works. Asking questions is what language learners do, even children, aaa.

The teacher is not always going to be there.

[aaa]

To be able to gerenate your own sentences, you need to know how the language works. Asking questions is what language learners do, even children, aaa.

The teacher is not always going to be there.

Absolutely! :)
I didn't even mean to argue

I just wanted to say that not everything can be clarified with grammar rules :) Something is gotten to comprehend as person became more experienced. And sometimes it is better to take something, you can't understand, as given until it gets clear. And it will. All above is IMHO.