Swimmers must be very strong in order to build up speed because of the high resistance of the water. Runners, , must struggle against the heavy resistance of the air and ground.
A. generally
B. similarly
C. naturally
D. probably
网友回答
A. generally
(答案→)B. similarly
C. naturally
D. probably
解析：游泳者与赛跑者相比较，有相似点，故选B。