The group of research workers are said to ________ to the dangerous nuclear radiation while they carried out their rescue task
A.be exposed
B.have been exposed
C.exposed
D.be exposing
网友回答
B解析考查非谓语动词。are said to do…据说……，所以排除C；且动词expose和逻辑主语The group of research workers是动宾关系，所以要用不定式的被动形式，排除D；expose这一动作发生在主句谓语动词are said之前，所以要用不定式的完成被动式。所以选B。