My sister is determined. ________ she has made up her mind, nothing can change it.

A．Though

B．Once

C．Unless

D．Until

48岁，女性，突然胸闷痛，心悸，心电图示Vl～3有深而宽的Q波，ST段抬高，伴有室性期前收缩，二联律形成，抢救中突然抽搐，最可能的原因是

A．Ⅲ度房室传导阻滞

B．心室颤动

C．心脏停搏

D．心房颤动

E．室性心动过速