英语语法：—Why do you look worried?—Fred left the company half an hour ago.His work ________ unfinished since.A.left B.was left C.has left D.has been left选哪个,为什么?
问题描述：
英语语法：—Why do you look worried?
—Fred left the company half an hour ago.His work ________ unfinished since.
A.left B.was left C.has left D.has been left
选哪个,为什么?
答