I would have told him about the change of time for the class, ______to class last time.
【正确答案】 C
【答案解析】解析:本题考查虚拟语气的用法。主句用的是would have told,表示对过去事情的虚拟,所以从句要相应地用过去完成时if he had come,if省略了,句子的助动词提前,倒装,故选D。