问题补充:
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
答案:
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。