Every society has its own ______.

A．planned systems

B．controlled norms

C．recognized boundary

D．established sanctions

男，48岁，气管插管全麻下行腹腔镜下胆囊切除术，术中监护仪突然显示心电图波形消失，你首先应做什么？（）

A.立即检查心电图电极是否脱落，重新接好心电图电极

B.摸颈动脉搏动

C.立即观察呼吸是否停止

D.立即测血压

E.立即重新启动监护仪