Question

【题目】---Who is knocking on the door?

---It ____ be the milkman. He sends the milk to me every day.

A. should B. can’t C. must D. need

Answer 1

【答案】C

【解析】

句意：谁在敲门？ --肯定是送牛奶的人，他每天都给我送牛奶。A. should应该，B. can’t 不能，can’t be”意思是不可能，表否定推测; C. must必须，must be“肯定是”，表肯定推测，D. need需要。从问句以及答句“He sends the milk to me every day.”可知这里表示肯定推测，所以用must be，故选C。