【题目】He is really nervous. He ______ back and forth all the night waiting for the results.
A. had walked B. has been walking
C. walked D. is walking
在线课程【答案】B
【解析】
试题分析：考查现在完成进行时。本句的时间状语是all the night整个晚上。现在完成进行时表示动作的持续性和反复性。句意：他真的很紧张，整个晚上他一直走来走去在等待结果。故选B。