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Hi. I have been trying to get a handle on the use of past perfect in various sentencial situations and came to a tentative conclusion that it is generally used to note clearly the time sequence involved, lacking any available clues that will show the sequence clearly in the text. I also think past perfect is used when an action or incidence has clearly occurred in the past and noting of it needed to make the sequence clear. Having said all this, I still am not confident on the use of it. What should I do to get a clear idea as to when and how to use the past perfect tense clearly?

What I would like to ask you for is some examples where the use of past perfect is optional since the sequence is clear. One example I can think of is this.

He bought what he had been was asked to.
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Here is my best explanation.
Past perfect tense tells us that an action started in the past and completed in the past.
It is required if a clause indicating the time reference related to the action's ending point (underlined in examples below) is in the sentence.
1) She had been living in Oregon for three years when she got the job offer in Washington.
2) I was just about to pay for my groceries when I discovered that I had left my wallet at home.
3) Joe had just set out on his morning jog when it began to rain.
4) She wanted to finish what she (had) started the month before. (optional)
5) Ten inches of rain had fallen since the storm had begun, and water was already spilling over the river banks.

Also past perfect is used in the subjunctive mood to state a wish about changing something in the past..
I wish I had studied harder in school.
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Anonymous some examples where the use of past perfect is optional since the sequence is clear.
Hi,
I grabbed these from Google, with a search for "had." Some may be what you're looking for. It seems to me that technically the past perfect is not needed for time sequence purposes. That is, the context seems to cover it. But sometimes it does create a certain flavor.

For example, in the last one, the use of past perfect suggests a greater sense of completion and resolution than would simple past.
_________________________________________________________________

Henry Paulson, the Treasury secretary at the time of the initial A.I.G. bailout, had previously been Goldman’s chief executive. ...

Fox News host Sean Hannity falsely asserted that Sen. John McCain had "been against the AIG bailout since the very beginning.

I stayed up until about 2:30am that night, chain smoking and talking to friends who saw my tweet and had responded - THANK YOU.
"We found a list of people he worked with, people who had done him wrong,"

The homeless man who broke into my house was obviously homeless because he wore a suit that had been a great deal too short. ...

Brett Favre had committed to Tampa Bay last off-season before abruptly being traded to the Jets
Edit. I guess the third one is not right. We need the past perfect to show that the friends responded before he was talking to them.
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Hi.

You wrote:

2) I was just about to pay for my groceries when I discovered that I had left my wallet at home.

3) Joe had just set out on his morning jog when it began to rain.

I think for no. 2, the use of past perfect (indicated in bold letters) is optional and not required as you said. Please tell me if I am wrong. I think for no. 3, whether past perfect is right or past is right depends on where you want to put one sequence on, in the past of the other event or future of the other event.

I think they don't represent cases in which past perfect is required. Please tell me if I am wrong.