Learn English – Using “is” and “are” with Verb

Obviously there's a lot of confusion around the perfect tense, and we could fill volumes with descriptions and explanations of how it's used. However the thing to bear in mind is that it is basically a present tense, where present refers to whatever point in time the speaker is in when he uses it. With that as a reference, the perfect covers a timespan from a point before that "present" and up to it.

I have been writing this letter for an hour.

Here the "present" is now, and the timespan began an hour ago.

I had been writing the letter when Tony arrived.

Here the "present" is the point in the past when Tony arrived and the timespan is an unspecified period before that point. It simply describes what was going on before and up until the point that Tony arrived.

With the present perfect, you can mention when an action began, but you can't use any temporal that would suggest that you're referring back to the event as a finished, completed action at any point in the past, because, remember, it is for all intents and purposes a "present" tense - so it always refers to now. So *I've seen him yesterday - doesn't work because yesterday is over. However you can say: I've seen him today - if today is still today when you say it. At the end of today, you would have to say, looking back, I saw him today. (This may not be so in British English - I couldn't tell you. They often use the present perfect where we use the simple past).

The past perfect is different in this respect; You can refer to an action that continued or was valid up until the referenced point in the past as a completed action: He had written a novel in 2013. It simply cites it as an accomplishment of sorts - an action that was completed by that point in time.

Using the progressive simply implies that it was a repeated or ongoing action:

He had been writing a letter

= this is what he was engaged in up until the point referenced in the account, but not a completed action.

Also note, that the perfect is open ended; the action is understood to have started at a point before, continued or been valid through to the point reference (now or then) and may or may not continue. That is why: I haven't seen him today = not yet, not so far... but I may still see him at some point before the day is over.

I realize this is probably a vague answer to your question - more of a general overview. If you have any specific points you'd like me to clarify, that I missed, please ask. I've been teaching the perfect to Russians for a year and have gotten pretty good at it :)

Example A:

1) "...had belonged to" could be correct, but only if "the time" is a period prior to some other event in the past. For example:

• When they were arrested, they had belonged to the Congress Party for three years. (The past perfect refers to something spoken of from a past perspective, which occurred farther in the past)

Otherwise, it's simple past:

• When they were arrested, they belonged to the Congress Party.

2) You cannot use - "...were belonged to...".
The verb "belong" is intransitive, thus it cannot be made passive. But you could say "were members of...". which is the simple past, and equivalent to "belonged to... To put that into past perfect, "had belonged to" (as above) is equivalent to "had been members of". So...

• When they were arrested, they were members of the Congress Party.

or

• When they were arrested, they had been members of the Congress Party for three years.

3) see #2. Never use "were belonged to".

Example B: 1) You are correct, it should be "has been reported".

But if you mean nobody has reported the accident to the police, I would have said (AmE)

• No report of the accident has been {filed/made} at any police station.

or, simply

• The accident has not been reported to any police station.

It's not a "case" until after a report has been filed and the police begin to investigate.