present perfect

[Julie17]

Are the tenses in the following sentences correct? Would other tenses also be possible (in British English)?
a) I haven't smoked for two weeks. I've stopped.
b) Peter didn't smoke for two weeks, but then he started again.
Thanks,
Julie

[rewboss]

They're correct, and I don't think you could use different tenses.

The present perfect links a past action with the present (usually). In sentence a), the past action (stopping smoking) is linked to the present (you still don't smoke). In sentence b), the past action is complete: Peter's short-lived smoke-free period has now ended and does not relate to the present.

[freddie]

Are the tenses in the following sentences correct? Would other tenses also be possible (in British English)?
a) I haven't smoked for two weeks. I've stopped.
b) Peter didn't smoke for two weeks, but then he started again.
Thanks,
Julie

Personal view,not necessarily correct:

a )"I have not been smoking for two weeks" or "I have not smoked since two weeks ago".I have stopped.


b)"Peter had not been smoking for two weeks" or "Peter did not smoke in two weeks before(some past time point) ",but then he started again.



"For" is used to say how long an action or a situation lasts. "Smoke" is a short action,it does not last.

[Julie17]

Rewboss, thanks for the feedback. Have you also got a good explanation for the tenses with "stopped" and "started"? My students sometimes argue that the situations are similar. The action of stopping or starting only lasts an instant, but in both cases they also relate to the present (b: He still smokes.)
Julie

[rewboss]

The simple past is used when the effect of the action on the present either no longer applies or is not important.

"Peter didn't smoke for two weeks..."

Here, we have a period of time which is completed -- the two weeks of Peter's smoke-free lungs are over. The action has no connection to the present any more, so there is no way we can use the present perfect.

"...but then he started again."

Maybe he still smokes. Or maybe he gave up again later, and this time he's successfully fighting temptation. This sentence doesn't say whether or not he smokes now; it refers to a past action but doesn't connect it to the present.

If we want to make it clear that Peter is still smoking, then we write:

"...but he has since started again."

Now it's clear.

If you students say that in your example b, Peter still smokes, they are making an assumption. There is, however, nothing in the grammar that warrants this assumption.

Confusion arises because there are similar tenses in German, but the choice between them is largely a matter of style (the perfect in spoken German, the preteritum in written German). Germans would say, "...aber er hat wieder angefangen", or write "...aber er fing wieder an", and assume -- unless the text specifically says to the contrary -- that Peter smokes today.