同学你好，该知识点来自沪江网校《英语零基础直达大学六级【双11专享班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
We arrived at Uncle Bear's house, in front of which is a swimming pool.
这里in front of 是个介词词组，在定语从句的前面。
这样一来，in front of which这个介词短语，也就是地点状语，就在谓语is的前面，主语a swimming pool在后，这就形成了倒装。
本来的结构是a swimming pool is in front of which

We arrived at a farm house, in front of which is a mountain.我们来到了一个农庄，在这个农庄的前面有一座大山。
in front of which 引导一个定语从句，介词短语位于which前，后面的分句要倒装，谓语is到了主语a mountain之前。

They arrived at a house, in front of which sat a small boy.
他们来到了一幢房子，房子前坐着一个小男孩。
谓语sat提到了主语a small boy前

祝同学学习进步~