I can't believe what he says because he is _______ changing his mind. .

A．regularly

B．steadily

C．suddenly

D．constantly

男性，65岁，诊断为急性心梗入院，住院第3天患者突然呼吸困难，青紫，神志不清，四肢抽搐，听诊心音消失，颈动脉搏动消失，此时首选（）

A.安置心脏起搏器

B.立即做心电图，了解是否停搏或室颤

C.心内注射肾上腺素

D.胸外心脏按压及人工呼吸

E.静脉滴注利多卡因