“英语语法网”上的这篇文章或许能解决你的问题：

http://www.yygrammar.com/Article/201104/2154.html

关于 from which 的用法比较好理解，这里主要说说 from where 的用法。from where 主要有以下两个用法：

用法一：用于引导非限制性定语从句，在意义上相当于 and from there（从那儿）。如：

He hid himself in a tree, from where he could see the enemy in the distance. 他躲在一棵树上，从那儿他可以看到远处的敌人。

We went up to the roof, from where we had a good view of the procession. 我们爬上屋顶，从那儿可以很好地观看游行。

用法二：可视为where前省略了the place，即这样用的from where 相当于from the place where，意思是“从……的地方”“离……的地方”。如：

From where I stood I could see everything clearly. 从我站的地方我一切都看得清清楚楚。

The car stopped short only a few inches from where I stood. 汽车在离我站的地方仅几英寸处突然停住。

The school was only a few blocks from where she lived. 学校离她的住所只有几个街区的距离。

若遇到前面是地点名词的先行词，如何判断用 where 还是 from where 还是 from which? 请看下面一个句子：

I have bought that house, _____I can enjoy the beautiful scene of Yangpu Bridge .

我们认为这道题填 where 和 from where 语法上都可以（但不宜填 from which），但两者在意义上稍有区别：

I have bought that house, where I can enjoy the beautiful scene of Yangpu Bridge. 我买下了那栋房子，在房子那可以欣赏到杨浦大桥的美景。

I have bought that house, from where I can enjoy the beautiful scene of Yangpu Bridge. 我买下了那栋房子，从房子那可以欣赏到杨浦大桥的美景。

在许多情况下，用不用 from 不会导致语法错误，但会导致语义变化（通常情况下是，如果没有 from，意思会不够明确和清楚）。比较：

He hid himself under the bed, from where he could hear what they were talking. 他躲在床下面，他可以从床下听到他们谈话。（句中的 from where 可理解为 from under the bed，意思是“从床下面”）

He hid himself under the bed, where he could hear what they were talking. 他躲在床下面，在床那儿他听到他们谈话。（句中的 where 可指为“在床边”“在床上”“在床下”等，意思不够明确）