So many natural disasters are believed___________over the recent years because of the frequent unreasonable mankind activities.

A．to have come about

B．to come about

C．coming about

D．to be coming about

男，60岁，肥胖。行右股骨外科颈骨折开放复位术，硬膜外麻醉效果不佳改全身麻醉，因声门显露困难反复试插管期间，患者出现室颤。静脉快速诱导后患者突然出现室颤

应继续进行的处理措施是（）

A.以头部为重点的低温疗法

B.高压氧治疗

C.持续滴注呼吸兴奋药

D.静脉注射催醒药物

E.控制性降压