"Jestem członkiem tej grupy."

Translation: I am a member of this group.

[Kulink]

The implicit "ja" is in nominative/mianownik, and "członkiem" is in instrumental/narzędnik, what case is "tej grupy" in?

[mihxal]

Genitive

[Gatu77]

She has intonation as if she is asking.

[Jellei]

Yeah, the audio has a wrong intonation probably more often than a correct one :/

[Hel667660]

Why can't the a be omitted from the answer? Is "I am member of this group" really wrong? No native English speaker, therefore the question.

[Jellei]

Well, you just can't do it with countable nouns.

[AnnaKupcov]

Couldn't it also be "I'm (a) part of this group?"