Can we use the time expression (... ago) in past perfect tense?

Question

I've read it somewhere that the time expression (... ago) (e.g. two days ago, two weeks ago, etc.) is only used in the simple past.

But in the exercise on unit 35, Advanced Grammar in Use I found this sentence:

He claimed that he had been to the paint factory two weeks ago.

The instruction is correcting the tenses in the that-clause, and the answer key says it's correct. It also suggests that the sentence might be written in simple past (went) without an exception regarding the time expression. Is the sentence above fine?

Answer 1

This sentence is incorrect. It's acceptable in speaking, but not good at all in writing. Without a specific context around this sentence, it's a poor choice for an otherwise excellent series like the Grammar in Use books.

In this sentence, someone had previously said something like, "I went to the factory two weeks ago". This sentence is now being reported, so according to the normal rules of reported speech, the reporting verb ("claim") and the times in the sentence get shifted to the past. So, "went" is shifted to "had gone". The expression "two weeks ago" always and only means "two weeks before the present time", so "two weeks ago" should be shifted to "two weeks before/earlier."

But you can also report speech without shifting the times back, including the reporting verb. This way of reporting speech asserts the speech being reported is still true now.

So if, for example, "he" said those words this morning, then his "two weeks ago" still refers to two weeks before the present time, so everything can remain in the same time:

"He claims that he went to the factory two weeks ago."

It doesn't make sense to have "ago", which is rooted in the present time, in a sentence about something said in the past. The meaning is that someone in the past claimed to have gone to the factory two weeks before the present time, rather than the time he was speaking.

Answer 2

ago- (at) a certain time before now, before- (at) a certain time before then

two weeks ago= two weeks before now

two weeks before= two weeks before then (before a past time)

Ago is usually used with the simple past tense. (NOT with the present perfect or the past perfect)

He went to the paint factory two weeks ago. How long ago did it happen? It happened a long time ago.

We usually use before or earlier or previously with the past perfect tense.

He had been to the paint factory two weeks before. He claimed that he had been to the paint factory two weeks before. We met in the same restaurant where we had met three years previously.