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

男性，52岁，原有劳累型心绞痛，近2周来每于清晨5时发作，疼痛持续时间较长入院，住院期间发作时心率50次／分，早搏4~5次／分，血压95/60mmHg，心电图Ⅱ、Ⅲ，aVFST段抬高，加用硝苯地平后未再发作，应用硝苯地平机制是（）。

A.增快心率，增加心排，改善心肌供血

B.减慢心率，降低心肌耗氧

C.缓解冠脉痉挛

D.提高血压，改善心肌灌注

E.增快心率，消除早搏