【单选题】Hearing the ____ story, the little boy had a ____ expression on his face. [ ]
A.
frightening; frightening
B.
frightened; frightened
C.
frightening; frightened
D.
frightened; frightening
【单选题】If the little boy had been given the best medical care,he____.
【多选题】对于任意两事件A和B,与A∪B=B等价的是______。