考查虚拟语气。根据前半句可知该句是省略 if 的虚拟条件句，表示的情况与过去事实相反，所以主句谓语用 would ／ should ／ could ／might+have+ 过去分词的形式。相当于： If he had worked harder, he would have got through the exams. 故选 C 。