The boss the worker how to do it, or the accident couldn’t have happened.
A. can’t have told
B. ought to tell
C. could have told
D. mustn’t have told
网友回答
(答案→)A. can’t have told
B. ought to tell
C. could have told
D. mustn’t have told
解析：
试题分析:意为：当时老板不可能告诉工人如何做这件事（是对过去的推测），否则这个事故不可能发生。
在英语中，我们对过去的推测，常使用情态动词（not）+have done 结构，故选 A