问题
选择题
There is a policeman _____ the bus. He is watching the traffic.
A．in front of
B．in the front of
C．in the front
D．the front
答案
答案：A
in front of 介词短语表示“在……前面”（外部）; in the front of 介词短语表示“在……前面”（内部）; in the front 在前面; the front前方，前线，故选A。