the day before yesterday前不加介词,和yesterday一样的道理1.Dr.Smith looked in on the invalid the day before yesterday.史密斯大夫前天去看望那个病人.来自《简明英汉词典》2.The accident happened the day be...一定不能加还是有可以省略的？不加的，考试有考过选择题，yesterday和 the day before yesterday. 前面都不加介词