男，48岁，发作性胸痛1月，每次发作含硝酸甘油后缓解，考虑冠心病心绞痛。最常用的检查方法是

A．心脏X线摄片
B．心电图运动负荷试验
C．放射性核素检查
D．动态心电图
E．超声心动图

Carbon dioxide as a fire fighting agent has which advantage over other agents?（）

A.It causes minimal damage

B.It is safer for personnel

C.It is cheaper

D.It is most effective on a per unit basis