PRESENT PERFECT 1
I have Known him for 5 months: Lo conosco da 5 mesi
We have known each other for 5 months: Ci conosciamo da 5 mesi
I have known you for 5 months: Ti conosco da 5 mesi
I have know her for a long time: La conosco da molto tempo.
So If is indicated the duraction in the phrase, I will use "I + PP", otherwise the present form.
Are these examples corrects?