During the period of recent terrorist activities, people not to touch an unattended bag．
A. had always been warned
B. were always being warned
C. are always warning
D. always warned
网友回答
A. had always been warned
(答案→)B. were always being warned
C. are always warning
D. always warned
解析：考查时态。这里用过去进行时表示过去某个时候经常性的动作。