Past Perfect

[wotcha]

I had been knowing Alex since we were at college together.


Is this sentence grammatically correct? If not, why?
Also, is it possible to use 'since' with past perfect?.

[Raymott]

I had been knowing Alex since we were at college together.


Is this sentence grammatically correct? It not, why?
It's correct if you mean "knowing" in the Biblical sense (ie. having sexual relations with). But it still requires another event in the past to warrant the use of the past perfect. That is, until when had you been knowing Alex?
In normal English, though - if by "know" you mean to be acquainted with - it's not grammatical.

Also, is it possible to use 'since' with past perfect?.

Yes, it's possible to think of a context. But you probably wouldn't use "since" in any usual construction with the past perfect. Would you like to give a sentence with 'since' that you aren't sure about. If so, try to include at least two events in the past to ensure that your past perfect tense is necessary.

- You can use "since" meaning "because" with past perfect.