题目

By the time my mom _____ to our school, all others of my class ______ for home.A．got, leftB．got, had leftC．had got, had leftD．had got, left 答案：B解析:略–Must I go to medical school and be a doctor like you , Dad?--No, you _____, son, you’re free to make your own decision.A. can’t B. mustn’tC. shouldn’t D. needn’t