The sudden fire caused a      in the cinema, and the crowd all ran away in all directions. [ ]

A. risk

B. panic

C. survey

D. surprise

吗啡中毒引起呼吸困难的主要原因是（）

A.兴奋呼吸中枢

B.使支气管痉挛

C.使肺淤血

D.肺泡弹性减弱

E.呼吸中枢受抑制