Housewarming parties get their name from the fact that a long time ago people would actually bring firewood to a new home as a gift. This was so that the person could keep their home warm for the winter. Now most homes have central heating and don’t use fires to keep warm.

老师好！

上面段落出自2020高考全国III卷阅读补全题目。蓝色粗体字的语法结构我作如下分析，想请老师指正一下是否得当：

1. This指代前面的事件:a long time ago people would actually bring firewood to a new home as a gift。

2. Be动词was作不及物动词作existed(不及物动词exist的过去式）的释义去理解。

3. So that引导一个目的状语从句。

上述分析如果不正确，烦请老师帮助纠正，谢谢！