The mother bought telescope for his son_____he could observe the skies ,which
问题描述：
The mother bought telescope for his son_____he could observe the skies ,which
made the son very happy
1.whom
2.which
3.for whom
4.through which
要原因
答
4
先行词是telescope 从望远镜中观察用 observe through the telescope
所以选through which