I soon found that the work I was doing by someone else — in other words, I was wasting my time.
A. had already been done
B. has already been done
C. would be done
D. have already been done
网友回答
(答案→)A. had already been done
B. has already been done
C. would be done
D. have already been done
解析：主句I soon found是一般过去时态，宾从that the work 要用过去时态的某种形式，排除B,D；且工作已经被别人做了，要用过去完成时态。I was doing是定从，修饰the work。选A。