In many places in China, _____ bicycle is still _____ poplar means of transportation. [ ]

A. a; the

B. /; a

C. the; a

D. the; the

鱼类内耳起平衡作用的主要部位为（）。

A、椭圆囊和球囊

B、球囊与半规管

C、椭圆囊与半规管

D、球囊