I am familiar with the verb ending - 잖아, as in 숙제를 하라고 내가 말했잖아! (I told you to do your homework, didn't I?) But I have a question: can 잖아 also be used when the main verb in the sentence is 이다? For example, if I want to say, "I'm American, aren't I?!", can I say, 내가 미국인이잖아! Somehow that sounds weird to me... Thanks for any help!