We such great achievements without your efforts. Thanks a lot.
A. can’t have made
B. couldn’t have made
C. were unable to make
D. are unable to make
网友回答
A. can’t have made
(答案→)B. couldn’t have made
C. were unable to make
D. are unable to make
解析：
这题考查情态动词对过去的虚拟，couldn’t have done“过去不可能做…，而实际上做了”，句意是：没有你的努力，我们不可能取得这么大的进步，（而实际上取得了）。选B。