问题
选择题
---- What happened to you?
---- I ________ in the street when someone patted me on the shoulder, which frightened me.
A．was about to walk
B．was walking
C．had walked
D．walk
答案
答案：B
题目分析：句意：你发生什么事情了？--我正走在街上，这时有人拍我的肩膀，这使我很害怕。这里用了过去进行时，表示when someone patted me on the shoulder这个时候，真正发生的事情，所以选B。