【正确答案】 B

【答案解析】hear sb．do sth．听到某人干某事。在hear后的不定式作宾语补足语时，不定式符号to通常省略。但是当该结构变为被动语态时，作宾语补足语的动词不定式要加to。如：I saw him come out of the school变为被动语态He was seen to come out of the school。类似这种用法的词还用watch，feel，make，let等。