"Can I take your watch?"
Translation:Puis-je prendre ta montre ?
DuoLingo sometimes takes kind-of a "tough love" approach to teaching. Sometimes, they let you get something wrong because it makes you pay close attention to the correct answer. Don't forget that the key to foreign language is not getting everything right the first time, it's getting it right on the second, third, fourth, fifth, sixth...
The "rule" in French is that every single phrase is an exception to the rules. Seriously, there's almost no point in trying to learn any rules, because not one of them is ever consistent. It's easier just to get used to "puis-je" meaning "can I" and not worrying about the reason behind it.
So "je peux prendre..." would be "I can take... if I wanted to/if I felt like it", rather than "would it be ok if I were to take..."? And the correct use of the inverted form of pouvoir in the first person is "puis-je", pronounced as "pweej" (sorry, can't do proper phonetics). Is that right?
Watch this difference between English and French: Possessive pronouns agree with only the the subject in English, but in person with the subject and in gender and number with the object in French.
ex. 3rd person sing. subjects: His car = Sa voiture. Her book = Son livre. His boats = Ses bateaux.
3rd person plur. subjects: Their car = Leur voiture. Their book = Leur livre. Their boats = Leurs bateaux.
Subject tells you which row to pick, object tells you which pronoun from the row to use.
French people mess this up in English: My French friend says things like "My wife has a freckle on his nose."