They have known each other since 1987

[AZ679]

(I found this question from another user on a wrong folder. It is also my question)


Page 106, Manhattan SC book, 5th Edition

They HAVE KNOWN each other since 1987.

How is the meaning of the above sentence different from "They know each other since 1987."

Can simple tense be used here in place of present perfect? If not, what is the reason?

[RonPurewal]

in that kind of usage, the present represents...
... 1/ a general truth, independent of a timeframe, or
... 2/ something that is important only because it is true right now.

1/
Blood circulates through the human body.
The sun comes up in the east.

2/
No introductions will be needed at the party, since you know everyone who is going to come.

--

if a timeframe is mentioned, then the sentence is at cross-purposes with both of these, so the present cannot be used.

[RonPurewal]

does your first language happen to be a western european language?
if so, then your confusion would make sense here, because, in many of those languages, this sentence DOES use the present tense.
e.g.,
french (Ils se connaissent depuis 1987)
spanish (Se conocen desde 1987)
catalan (Se coneixen des de 1987)
etc.

in english? nope.

[AZ679]

does your first language happen to be a western european language?
if so, then your confusion would make sense here, because, in many of those languages, this sentence DOES use the present tense.
e.g.,
french (Ils se connaissent depuis 1987)
spanish (Se conocen desde 1987)
catalan (Se coneixen des de 1987)
etc.

in english? nope.

Thanks.
No, my mother tongue is Persian.

[RonPurewal]

does farsi write it that way?

farsi is another indo-european-family language, so it's not totally unlikely.

[AZ679]

does farsi write it that way?

farsi is another indo-european-family language, so it's not totally unlikely.

Well, that depends; we can say a sentence using present perfect, if we use their becoming familiar as subject:

Their knowing each other has started since 1987

But if take the two persons as our subjects, we naturally use:

They know each other since 1987
(This means that they are both alive and still know each other)

But these are what seem 'natural' to me. I do not know the exact grammatical rules and standards of formal, written Persian!

[RonPurewal]

(:

thanks.

"we do this since (date)" exists in most western european languages too.
but not in english.