A question about "when"

when was your interview ?
this sentence is correct ? why ?

but we do not know it means when did the interview begin or when was the interview over ?
so i feel it is not correct

but we do not know it means when did the interview begin or when was the interview over ?
so i feel it is not correct

>>>>>>>>>>>>>>

Isn't that the purpose of the question form, Guest; to find out these issues of time?

It means "When did the interview begin?"
You can answer by saying, "The interview was at 3 o'clock", meaning "The interview began at 3 o'clock".

You do have another choice, however, if you want to be even more specific. You can answer, "The interview was from 3 o'clock to 4 o'clock". This is giving more information than was asked for, but there's no harm in that! (Usually the questioner is not expecting such a detailed answer.)

Another choice is to interpret the question as more general and answer "The interview was on Monday" or "The interview was last week". In these cases the entire event takes place within the specified time period and the focus on the beginning of the event is neutralized.

Normally, "when is", "when was", with an event which takes more than a moment singles out the beginning of the event.

When is the concert? When was the exam? When was his surgery? When is the wedding?

CJ