问题
选择题
When Steven suddenly remembered that he had left his mobile in the office, the train was already ________.
A．on the go
B．on the rise
C．on the run
D．on the move
答案
答案：D
题目分析：考查介词短语。A忙碌；B上涨；C在逃，奔波；D在移动中。句意：当史蒂夫突然想起来他的手机落在办公室的时候，火车已经开动了。故选D。