He all his aims. But his efforts in the past few years have been praise-worthy.
A. could have achieved
B. wouldn’t have achieved
C. must have achieved
D. may not have achieved
网友回答
A. could have achieved
B. wouldn’t have achieved
C. must have achieved
(答案→)D. may not have achieved
解析：考查情态动词的完成式：句意：他可能不会达到所有的目标，但是他过去几年的努力是值得表扬的。could have done，过去可能做了…，wouldn’t have done过去本来不会做而做了， must have done过去一定做了，may not have done过去可能不会做，选D符合句意。