题目内容
【题目】She ___________ clean the classroom today.
A.isn't have to
B.don't have to
C.doesn't have to
D.have to
【答案】C
【解析】句意：今天她不必打扫教室。短语have to+动词的原形，表示必须做某事；主语是第三人称单数。其否定形式要用助动词does+not，根据句意，故选C。
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题目内容
【题目】She ___________ clean the classroom today.
A.isn't have to
B.don't have to
C.doesn't have to
D.have to
【答案】C
【解析】句意：今天她不必打扫教室。短语have to+动词的原形，表示必须做某事；主语是第三人称单数。其否定形式要用助动词does+not，根据句意，故选C。