we arrange them in the order they happened in the story是什么从句

定语从句.意为：我们按照他们在故事中发生的顺序来安排（组织）他们.该句修饰主句中的order一词.引导此从句的关系代词是 in which 被省略了.完整的定语从句是：in which they happened in the story.在现代英语中,当定语从句修辞的词是 way/order 等时,引导从句的关系代词常常被省略.例如:This is the way (that/in which)we solved the problem.