what is the difference between I have seen and I saw- and how do we determine it in Itailian?
Same as me, this lesson is completely full of mistakes... I am almost giving up on DL...
It is because in Italian the present perfect is used to indicate something that happened more recently, for which in English it is more common to use simple past tense. So the preferred translation to English is not the literal one (i.e. present perfect), but the one that more closely approximates the actual meaning (i.e. past simple). Hope this helps!
Source: native Italian speaker
Yes, you're right.
Ho visto il coltello ieri. L'ho visto ieri / I have seen the knife yesterday. I have seen it yesterday.