I'm sure that I can say:
- I had eaten an apple before I went to school.
But as the question says, Can I use a specific time?
For example:
- I had eaten an apple in yesterday morning before I went to school.
Is this correct?
Edit:
Okay, reading from the comments, that word 'when' must have been a typo in my examples.
So, I would like to learn:
Is the past perfect sentence usually formed using a "compound sentence"?
And shall I take it that you cannot use specific time to form any past perfect sentence?
Best Answer
One can use the past perfect with an indication of time. It depends on context and what you want to say.
Such as they stand, and without further context, I would not use the past perfect in either of your sentences.
I ate an apple before I went to school.
I ate an apple yesterday morning before I went to school.
But one can imagine contexts where the past perfect would be possible.
I had eaten an apple before I went to school, but I was still hungry when I got there/by the time I got there.
I had eaten an apple yesterday morning before I went to school, but I was still hungry when I got there.
In these sentence the past perfect is justified to describe an action (eating an apple) that precedes another action (going to school) in a past context. If nothing in the context specifies that you are talking about a situation in the past then the past perfect is not justified.
It would sound weird to say:
I'd rather use the simple past:
The past perfect expresses the idea that one action occurred before another action in the past.
Time indication is perfectly acceptable with the past perfect and could be an actual time of course: