as引导让步状语从句主谓倒装的情况?是不是只有当形容词提前时才能主谓倒装?如果是,什么情况下要主谓倒装,什么情况下不需要?比如：Young as Jane is,she can dress herself 的说法是正确的吗?为什么可以用Difficult as was the task,they finished it in time.

as引导让步状语从句主谓倒装的情况?
是不是只有当形容词提前时才能主谓倒装?如果是,什么情况下要主谓倒装,什么情况下不需要?比如：Young as Jane is,she can dress herself 的说法是正确的吗?为什么可以用Difficult as was the task,they finished it in time.