答案：C

题目分析：考查虚拟语气。if虚拟条件句常把if省略，把were，had，should提到句首。对现在虚拟，if从句用一般过去时，be动词用were，主句用would do sth；对过去虚拟，if从句用过去完成时，主句用would/could ahve done sth；对将来虚拟，if从句用过去时/ were to/should+动词原形，主句用would do sth。根据主句would not have gone to可知，这里是对过去进行虚拟，if从句用had done，故选C。