问题
选择题
He must be helping the old man to water the flowers，________？
A．is he
B．isn't he
C．must be
D．mustn't he
答案
答案：B
must在此表猜测，是“一定”之意，此时反意疑问句部分以must之后的动词为准，所以B项正确。
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He must be helping the old man to water the flowers，________？
A．is he
B．isn't he
C．must be
D．mustn't he
答案：B
must在此表猜测，是“一定”之意，此时反意疑问句部分以must之后的动词为准，所以B项正确。
