问题补充：
We were told that Mr Green the office for a few minutes when we arrived.
A. has been away from
B. had left
C. had been away from
D. has left
答案：
A. has been away from
B. had left
(答案→)C. had been away from
D. has left
解析：句意：有人告诉我们，当我们到达办公室的时候格林先生已经离开好几分钟了。由于句子当中含有表示一段时间的状语for a few minutes，故谓语动词必须用延续性动词；leave离开，是一个非延续性动词，当与一段时间连用时，必须换成be away from。根据when we arrived可知主句必须是过去时态，所以选C。
