请教一道英语语法填空

题目

请教一道英语语法填空
请高手指教.
I remember the years my three children started school and how I tried to prepare them for things that others might use ___could hurt them.横线答案是that,如何理解

答案

I remember the years my three children started school and how I tried to prepare them for things (that others might use )第一个定语从句(___could hurt them.)第二个定语从句我还记得我三个孩子要上学那会,...