1.from which = from (the top of the moutain) 从山顶
2.from where = from (out of which) = rrom (out of the window) 从窗子外面
from是一个特殊的介词,它不但可以加名词/代词形成介宾短语,而且还可以加介宾/副词.
如：I come from China.
The tiger jumped from behind the tree.
He has just retured from abroad.
此两题的区别在于对from后面的成分在句意上的不同的把握.