Now 70 years old, the British physicist, Pendry can’t remember a time when he was not ask

Now 70 years old, the British physicist, Pendry can’t remember a time when he was not asking a question as a kid, joking that he his parents to death.
A. should torment(折磨)
B. must torment
C. must have tormented
D. should have tormented

A. should torment(折磨)B. must torment(答案→)C. must have tormentedD. should have tormented解析：考查情态动词与虚拟语气。句意：现在，70岁的英国物理学家Pendry记得儿时，总是被问同样的一个问题，开玩笑说他一定是折磨死了他的父母。根据joking可知，事情不是真实的，用虚拟语气。must have done一定已经做了某事；should have done sth本应该做某事。故选C。

我明天再问问老师，叫他解释下这个问题