—Why do you look worried?
—Fred left the pany half an hour ago. His work unfinished since.
A. left
B. was left
C. has left
D. has been left
网友回答
A. left
B. was left
C. has left
(答案→)D. has been left
解析：受前一句left的影响，易误选B。题干中的since说明此处应用现在完成时态。从问句中也可看出来，此处强调动作对现在的影响，故要用现在完成时的被动式。