There is a bridge the river and the bridge many people are walking.A. over; over B. on; o

问题补充：

There is a bridge the river and the bridge many people are walking.

A. over; over

B. on; on

C. on; over

D. over; on

答案：

A. over; over

B. on; on

C. on; over

(答案→)D. over; on

解析：句意：河上有一座桥，许多人在桥上散步。over强调的是在一段垂直的距离之上，on表示在物体的表面，故选D