1.过去将来时是指,以过去某个时间为基准,在它的将来发生的事情.
2.翻译成汉语,two days later两天以后,the next day下一天(即第二天）.
eg.
He would come here two days later.(他2天后将来这里）
比较着给举一个例子：
He says:" I will come here two days later."(他说,我将两天后来这里）
--------------(一般现在时）
将此句变为转述的,即：
He said that he would come here two days later.(他说他将两天后来里）
-------(that从句为过去将来时）
和过去完成时意义吻合：
He had been here two days later.(两天后他来这了）
或
He had gone there two days later.(两天后他去那了）
eg.
He would come here the next day.
和上面例子同理：
He says:" I will come here tomorrow."
He said that he would come here the next day.
（过去时和完成时里的the next day都是由tomorrow来的）
本人英语专业,还有什么不懂的楼主可以再问
建议楼主看看语法书,熟悉确切的语法知识,这样就不难分析了.
语法生硬,也可以多多阅读,培养良好的语感,这样即使不死扣语法,平时遇到句子也会很容易理解的.