1．It is most instructive lecture that I _______ since I came to this school.
A. attended B. had attended C. am attending D. have attended
2．One Friday, we were packing to leave for a weekend away ______my daughter heard cries for help.
A. after B. while C. since D. when
3．--- How’s your new babysitter?
--- We ______ ask for a better one. All our kids love her so much.
A. should B. might C. mustn’t D. couldn’t
