According to my teacher I can say:
I don't know him yet.
However I should not ever say:
I haven't known him yet.
My question is whether I can say these three sentences:
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I haven't know him yet that long
-
I have known him for two years
-
I have known a lot of people not speaking English very well.
In case I can say them, where is the difference in comparison to my original examples where my teacher doesn't use present perfect (in her opinion should not be used)?
Best Answer
Part 1
The grammatical form of this sentence gives the sense of a one-off completed event. The word that makes this so is 'yet'. 'Yet' means 'so far'. So 'I haven't known him yet' means 'I haven't known him so far' or 'up until this point in time'.
Thus we might say, "I haven't kissed her yet" or "I haven't met her yet."
Both of those refer to an event that has a start and a finish. However, with knowing, it tends not to have a finish -- once you know something, you know it forever. (Alzheimer's or death excepted)
For this reason, the grammatical form of "I haven't known him yet" encourages us to think of a discrete event that has not yet taken place. This promotes the Biblical interpretation of the verb 'to know'. Therefore I would tend to read it as an old-fashioned way of saying "I haven't had sex with him yet."
Maybe your teacher prefers that you don't learn about archaic uses of the verb at this stage and so has excluded that possibility.
Full Definition of KNOW
transitive verb
1 a (1) : to perceive directly : have direct cognition of (2) : to have understanding of (3) : to recognize the nature of : discern
b (1) : to recognize as being the same as something previously known (2) : to be acquainted or familiar with (3) : to have experience of
2 a : to be aware of the truth or factuality of : be convinced or certain of b : to have a practical understanding of
3 archaic : to have sexual intercourse with
Merriam-Webster
Part 2
Firstly I'll correct the sentences.
I haven´t known him that long yet.
This sentence is correct. Knowing someone for a length of time is a discrete event. It starts at some point in time and ends at another point in time. It might occur in the following conversation:
"How long have you known John for? Is it over a year?"
"No, I haven´t known him that long yet. In fact the anniversary of our meeting is next week."
I have known him for two years.
Again this is correct. A period of two years has a beginning and an end. Thus 'for two years' describes the length of the period you have known him. The use of present perfect tells us that the end of the period of time in question is now. If the sentence had been, "I knew him for two years" then we understand that you no longer know him (maybe he died or left the country).
I have known a lot of people who didn't speak English very well.
The impression given by the sentence is that you used to know these people or you knew them for a short while but you no longer know them. Your acquaintance with them is over.
I hope this helps.