He___in the classroom just now , he ___be there now A. heard to sing , may B.was heard sing

问题描述:

He___in the classroom just now , he ___be there now A. heard to sing , may B.was heard sing
He___in the classroom just now , he ___be there now     A. heard to sing , mayB.was heard sing ,must    c.heard sing , must.  D.was heard to sing , may

B 第一个空主动语态是hear sb do sth ,变成被动是be heard do sth
第二空must表示肯定推测,一定还在那里