[ ] must we finish the exercise today no ,you { }A mustn'tB don't haveC don't have toD needn't to并说明原因

[ ] must we finish the exercise today no ,you { }A mustn'tB don't haveC don't have toD needn't to并说明原因
[ ] must we finish the exercise today no ,you { }
A mustn't
B don't have
C don't have to
D needn't to
并说明原因

[ ] must we finish the exercise today no ,you { }A mustn'tB don't haveC don't have toD needn't to并说明原因
C
Must疑问句对应的回答是have to或need（不需要）
D去掉to 就对了