The experiment shows that proper amounts of exercise, if  __  regularly, can improve our health.

A．being carried out

B．carrying out

C．carried out

D．to carry out

抢救噎食病人的关键是：（）

A.抢救循环衰竭

B.保持呼吸道通畅、抢救呼吸衰竭

C.保护肝功能

D.护脑

E.以上均是