A. exercise B. exercising C. exercised
A. is belonging B. belong C. belongs
A. take B. took C. taking
A. isn't B. doesn't C. hasn't
A. working B. worked C. works
A. understanding B. to understand C. understand
A. playing B. played C. play
A. is trying B. tries C. has tried
A. they do cost B. do they cost C. cost do they
A. were B. have been C. are