Translation:The cat is drinking milk and I am paying.
I pictured a man getting in a bar with a cat, milk on the rocks please... I'm paying!
Why I can't say... The cat drinks milk and I am paying. I think it should be correct...
Why is 'the cat's drinking milk..' so wrong. Duo needs to try and understand apostrophies.
Because the apostrophe in your case is informal speech. The apostrophe here after cat denotes possession and hence the sentence "The cat's drinking milk" is grammatically incorrect. "The human's cat is drinking milk" here the cat belongs to the human. The apostrophe denotes that. In your sentence, the reader wonders the cat's what is drinking milk.
Actually 'the cat's drinking milk' is a totally valid contraction (not a possessive), spoken & written by English speakers all the time. It means 'the cat is drinking milk'. If Duolingo allows other contractions (& they do), they should allow this one too.
Craig, I think you may be confusing, 'the cat's', with, ''the cat is'' which is incorrect written English. Here the apostrophy does not indicate an abbreviation of, ''the cat is'' but rather, ''the cat's pocesses/owns (the item which follows). I.e.:-
''The cat is drinking milk.'', means the cat is lapping-up milk. Whereas, ''The cat's drinking milk.'', means, (the), 'drinking milk' belongs to the cat.
I was actually referring to contractions, not possessives. The point I was trying to make is Duo is happy with things like 'they're' for 'they are', or 'he's' for 'he is', but for some reason not 'cat's' for 'cat is'. The cat is drinking milk = the cat's drinking milk. Common parlance. Just one of the amusing foibles I guess.
This isn't correct when written. Its sloppy when a person says "where's the cat?" … "Oh, the cat's drinking milk". works for spoken, but you wouldn't (r at least shouldn't) write it like that. "He's" works because it is a pronoun, you wouldn't say "that's HE'S wallet" denoting possessive, you'd change it to HIS wallet.
Why 'bezahle' instead of just 'zahle'? What effect does the 'be-' prefix have? Does it make it somehow more in the present or more continuous?