He isn't in the school ,I think he ___ be ill .A.need B.shall C.must D.havt to ,为什么?

问题描述:

He isn't in the school ,I think he ___ be ill .
A.need B.shall C.must D.havt to
,为什么?

must表示推测

表示肯定推测
He isn't in the school
他不在学校,所以一定是病了