Question

---May I go out to play with my friends now, Dad?
---No. You ______ let your mother know first.
A. may                     B. need                    C. must

Answer 1

C

解析試題分析：句意：我可以和朋友一起出去玩吧，爸爸？不，你必須首先讓你媽媽知道。May可以；need需要；must必須。所以選C。
考點：考查情態動詞。