[alawton]

I feel for you. I've had students like that before. It is almost like their only goal is to discredit you. She is probably just waiting to pounce.

I will usually tell this kind of student to jot down any question that she has, so as not to disrupt the flow of the lesson. Explain to her that you have the whole class to think of when you are teaching. You can't stop every time this student has a question that will not really benefit the rest. If she does approach you with the question after class, just calmy answer it, or get back to her. I think you'll find that, with this kind of student, the goal is to fluster you instead of a sincere quest for knowledge of random technical grammar points. Making her wait will until after class will take some of her steam away. Good luck!