问题补充：
The experiment shows that proper amounts of exercise, if regularly, can improve our health.
A. being carried out
B. carried out
C. carrying out
D. to carry out
答案：
A. being carried out
(答案→)B. carried out
C. carrying out
D. to carry out
解析：句意：这项实验表明适量的运动，如果有规律的完成，可以改善你的健康。这里是省略了相同的主语及be动词，整句完整的话应该是：The experiment shows that proper amounts of exercise, if the proper amouts of exercise is carried out regularly, can improve our health.选B。
