since he has smoked a cigarette

[Fagin]

I've been pointed into this part of A Practical English Grammar, by A.J. Thompson and A.V. Martinet:

188 it is + period + since + past or perfect tense

We can say:
It is three years since I (last) saw Bill or
It is three years since I have seen Bill.

I last saw Bill three years ago or
I haven't seen Bill for three years.

It is two months since Tom (last) smoked a cigarette or
It is two months since Tom has smoked a cigarette.
He last smoked a cigarette two months ago or
He hasn't smoked a cigarette for two months.

But then there is another book, Advanced Grammar in Use, by Martin Hewings that says:

Note, however, that we use the present perfect in the time clause if the two situations described in the main clause and time clause extend until the present:
Have you met any of your neghbours since you've lived here?

The two books clearly contradict one another. Which one should I believe?

 

[jutfrank]

What's the contradiction?

 

[Fagin]

What's the contradiction?

The quote from the second book (which I believe) suggests that the sentence "It is two months since Tom has smoked a cigarette." implies that Tom is still smoking the cigarette. He's been smoking it for two months. Which is exactly the opposite of what is said in the quote from the first book.

 

[jutfrank]

"It is two months since Tom has smoked a cigarette." implies that Tom is still smoking the cigarette. He's been smoking it for two month.

No. Tom hasn't smoked any cigarettes for two months. If what you say were true, that would be one hell of a long cigarette!

 

[Fagin]

If what you say were true, that would be one hell of a long cigarette!

And that's exactly what befuddles me. But Martin Hewings is explicit on this matter. Let me repeat:

we use the present perfect in the time clause if the two situations described in the main clause and time clause extend until the present

Otherwise a different rule applies:

In a sentence which includes a time clause with since, we generally prefer a past simple verb in the time clause and a present perfect verb in the main clause. The time clause refers to a particular point in the past

which means that a perfect English sentence should read "It has been two months since Tom smoked a cigarette"

 

[GoesStation]

which means that a perfect English sentence should read "It has been two months since Tom smoked a cigarette"

You mean "an English sentence that comports perfectly with Hewings's rule as I understand it."

Your proposed sentence works OK, though an adverb would improve it: ...since Tom last smoked. The version with the present perfect works too. Can you fit the problem sentence into the rule if you understand the condition it has been two months as an ongoing one?

 

[Fagin]

Can you fit the problem sentence into the rule if you understand the condition it has been two months as an ongoing one?

No. Unfortunately. Let me repeat the rule again:

we use the present perfect in the time clause if the two situations described in the main clause and time clause extend until the present

 

[jutfrank]

Right, okay, I now understand what you're asking. Maybe Hewings is not being clear enough but I can't say for sure without reading the source. The fact of the matter is that both sources are right.

It is two months since Tom has smoked a cigarette.
It has been two months since Tom smoked a cigarette.

are both correct forms, and so you will hear both used. They are both equivalent to Tom hasn't smoked a cigarette for two months. I prefer to use (and teach) the latter.

 

[Fagin]

Maybe Hewings is not being clear enough but I can't say for sure without reading the source.

If you have the book you will find this in Unit 3, Section B.

The fact of the matter is that both sources are right.

It is two months since Tom has smoked a cigarette.
It has been two months since Tom smoked a cigarette.

are both correct forms, and so you will hear both used. They are both equivalent to Tom hasn't smoked a cigarette for two months. I prefer to use (and teach) the latter.

Isn't this because the former is a bit equivocal?

Ok! Thank you very much! It's 2 in the morning here and I need to have a sleep. Good bye.

 

[jutfrank]

If you have the book you will find this in Unit 3, Section B.

Thanks, but I don't.

Isn't this because the former is a bit equivocal?

Yes, I suppose so.

Ok! Thank you very much! It's 2 in the morning here and I need to have a sleep. Good bye.

You're very welcome. Me too.

 

[Tdol]

It is two months since Tom has smoked a cigarette.

The simple past works better for me than the present perfect.

 

[GoesStation]

Not for my AmE eyes. Although the simple present doesn't look wrong to me, I prefer It has been two months since Tom has smoked a cigarette.

 

[Phaedrus]

Renaat Declerck draws an interesting semantic distinction between the use of the present perfect and the simple past in "since"-clauses like this. I don't have the book (The Grammar of the English Verb Phrase) with me at the moment, but the distinction he draws is basically this. The present perfect in such clauses implies that the situation had the potential to happen again between then and now even though it didn't, whereas the simple past has no such implication. I can definitely feel the difference in certain cases:

(1a) It's been a month since I last ate there.
(1b) It's been a month since I've eaten there.

(2a) It's been five years since he died.
(2b) ?* It's been five years since he's died.

 

[jutfrank]

Renaat Declerck draws an interesting semantic distinction between the use of the present perfect and the simple past in "since"-clauses like this. I don't have the book (The Grammar of the English Verb Phrase) with me at the moment, but the distinction he draws is basically this. The present perfect in such clauses implies that the situation had the potential to happen again between then and now even though it didn't, whereas the simple past has no such implication. I can definitely feel the difference in certain cases:

(1a) It's been a month since I last ate there.
(1b) It's been a month since I've eaten there.

(2a) It's been five years since he died.
(2b)?* It's been five years since he's died.

Nice. I agree.