By the time he realizes he________into a trap, it’ll be too late for him to do anything about it. [ ]

A. walks      

B. walked

C. has walked  

D. had walked

病人左侧多根双段肋骨骨折，吸气时骨折处胸壁陷落，呼气时反而隆起。

应立即行（）。

A.手法复位

B.胶布固定

C.给氧

D.胸腔闭式引流

E.肋骨牵引术