具有二氢吡啶衍生物结构的抗心绞痛药是（）

A.硝苯地平

B.硝酸异山梨酯

C.吉非罗齐

D.利血平

When starting CPR on a drowning victim，you should（）.

A.start chest compressions before the victim is removed from the water

B.drain water from the lungs before ventilating

C.begin mouth-to-mouth ventilations as soon as possible

D.do not tilt the head back since it may cause vomiting