Question

【题目】— Could you come to my party tomorrow afternoon?
— Sorry, I _______. I take care of my little sister.
A.couldn't; have to
B.can't; may
C.can't; have to
D.couldn't; may

Answer 1

【答案】C
【解析】句意：--明天下午你能来参加我的聚会吗？--对不起。我不能，我必须照顾我的小妹妹。could you+动词的原形，起否定回答用can't；have to表示必须；不得不；may表示可以。根据题意，故选C。