By the end of last week, we a satisfactory solution to the problem.
A. have found
B. will be finding
C. had found
D. found
网友回答
A. have found
B. will be finding
(答案→)C. had found
D. found
解析：考查时态。By到….为止，与完成时连用；句中the end of last week又是指过去的时间，所以使用过去完成时。句意：到上个星期结束的时候，我们已经找到了这个问题的令人满意的解决方法。