It is about time we left here. Why use 'left' instead of 'leave'?

HongkieI saw this on an English tutorial video. Can we use 'leave'? What is the difference?Thank you.

It's one of the oddities of the English language. Yes, you can use "leave".

Thank you.

I can use 'leave' too? same meaning?

In my variety of British English we can use only a past tense: It's time we left/were leaving. A present tense is not possible: It's time we leave/are leaving.

An infinitive is also possible: It's time (for us) to leave.

Thank you, fivejedjon.
Any reason for that? What is the rule? How do I know when to use a past tense?

HongkieAny reason for that? What is the rule? How do I know when to use a past tense?

I suppose that originally the past tense was used as the remote/distancing tense, and would probably have been subjunctive:

It would be good if we were not here. (The reality is that we are still here.)
It's time (that) we were not here. (The realit

Thank you very much for the explanation, fivejedjon.