问题补充：
-- I’m exhausted. I on a project day and night.
-- You’d better have several days off after finishing it. Otherwise you might break down.
A. worked
B. have worked
C. work
D. have been working
答案：
A. worked
B. have worked
C. work
(答案→)D. have been working
解析：考查时态：句意：--我很累，我整天都在忙着这个计划。-结束后你最好休息几天，否则你会垮掉的。说明做这个项目是从过去到现在说话的时候一直进行的，有可能还要继续，用现在完成进行时，A是一般过去式，表示纯粹的过去的动作，B是现在完成时，表示过去的动作对现在的影响，C是一般现在时，表示一贯的行为，所以选D。
