haven't called
hadn't called
weren't to call
didn't call
本题考查虚拟语气的用法。根据this morning判断应该是发生在过去，与过去事实相反：从句：had + 过去分词；主句：would/ should/ could/ might + have + 过去分词。故选B。 句意：如果你今天早上没有给我打电话，我就错过了那个重要的会议。
