题目内容：

The best way to learn a foreign language well is ___ to an English environment.
A.to be exposed B.to expose C.to be exposing D.to have been exposed
Which one?Why?

优质解答

选A.expose是使暴露之意,这里需要用被动语态,所以B不对；C不是正确的形式；D是过去完成时态的被动语态,这里不应该用此时态.