用can,can't,could,may,must,have to填空.
用could,need,can't,may,must填空
用should,shouldn’t,must,mustn’t,needn’t,can’t ,may,have to 填空
用could,can,can't,must,mustn't need't may填空
用 can may must have to及否定形式填空
用can,can't,must或have to 填空
用can,may,must,can't,mustn't填空.
用can,may,must,can't,mustn't 填空
用can,must,musn't,have to,has to填空
用may,must,can,can't,should填空,
用情态动词should,may,must,can,could,ought to 填空
分析一下can may must could might could have
用can.can't,must,mustn't,will,have,to填空