"Beide trinken Kaffee."
Translation:Both of them drink coffee.
yup, that would be correct. (i know that for sure cuz i did that & it says correct)
I translated it "they are both drinking coffee" and it was marked incorrect. Grrr.
and without an article.. :) with article even nominative is Beiden at least that's what i could get from the link you provided... Danke