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

问题补充：

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

答案：

A. being carried out

B. carrying out

(答案→)C. carried out

D. to carry out

解析：考查状语从句的省略。if 后省略了it is,完整形式为：if it is carried out regularly，句意：实验表明适量的锻炼，如果定期执行的话，会提高我们的健康。故选C。