"My friend introduced his sister to me."

Translation: Mój przyjaciel przedstawił mi swoją siostrę.

[adamj57]

Mój przyjaciel zapoznał mnie ze swoją siostrą - that's the same!

[Jellei]

Yeah, sure. Added.

[AlisonSinc]

What is the difference in usage between 'mi' and 'mnie' here? I had 'mój przyjaciel przedstawił mnie jego siostrę' and it corrects it to 'mi'.

[Jellei]

"mnie" is the emphatic form, so it's used to contrast "me" and someone/something else. Also it's needed if you want to start a sentence with this word.

[AlisonSinc]

That is really helpful. I thought somehow it was a difference of case.

[Olly_1052]

"Mój przyjaciel przedstawił jego siostrę mnie" - Is it correct ?

[Jellei]

Sounds not natural. This is the situation which our learners create very often, when you put an unnatural stress on "me, and not someone else".

[Olly_1052]

Thank you.

[Sachiko382840]

Mój przyjaciel przedstawił mi swojego siostrę -- why is this incorrect?

[Olly_1052]

"swojego" is masculine

[Sachiko382840]

So, that means, if I use swój/swoja/swoje, shouldn't I follow the gender of the subject? So, "jego siostrę, but "swoją siostrę" ?? Duolingo doesn't explain grammar...

[immery]

it's like with mój, twój, nasz wasz- - like adjectives gender, number and case has to match the noun it describes.

jej, jego, ich - don't decline

[Sachiko382840]

Thank you for the clear explanation.

[Olly_1052]

In english: his(her, my, your, our, their) own sister (feminine), his(her, my, your, ,our, their) own brother (masculine), his(her, my, your,our, their) own window (neuter).
In polish: swoJA (feminine) siostra, swóJ (masculine) brat, swoJE (neuter) okno
https://en.wiktionary.org/wiki/Appendix:Polish_pronouns

[Sachiko382840]

thank you

[GresoTheGropaga]

NOPE, NOPE, NOPE. There's no way a native Polish speaker with an average intelligence would say something like that. It is "mój przyjaciel przedstawił mi SWOJĄ siostrę".

[Jellei]

There is a way if Michał introduces Piotr's sister to me. There are far worse sentences in the current version of the course. Most of them are caused by the fact that "swój" has been introduced a lot later than the 'normal' possessives.

We have fixed this in the new Tree 2.0 we're building, but as far as the current version is concerned... it's kinda pointless to find all the wrong ones and fix them. Provided that fixing them is even possible (that the given sentence is introduced after the introduction of "swój").