题目

I should not have laughed if I ________ you were serious. A. thought                              B. would think C. had thought                          D. have thought 答案：C 句意；如果我知道你是认真的，我就本不应该笑。根据句意可知，本句是与过去事实相反的虚拟语气，所以从句应用过去完成时。笼中有和各x只，数数脚一共有36只， 和和各有多少只？