The experiment shows that proper amounts
题型：选择题
问题：
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
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