Bicycling is good exercise; , it does not pollute the air.
A. nevertheless
B. besides
C. otherwise
D. therefore
网友回答
A. nevertheless
(答案→)B. besides
C. otherwise
D. therefore
解析:nevertheless副词,尽管如此;besides介词,而且,此外,除...之外;otherwise副词/连词,否则,不然;therefore副词,因此。句意是自行车是很好的运动,而且它不污染空气。故选B。