题目内容
在下面定语从句中，用适当的介词填空。
He bought a book yesterday, the author ________ which is a teacher．
He built a telescope ________ which he could study the skies．
The woman, ________ whom I learned the news, is a nurse．
The wolf ________ which the sheep was killed was shot．
The desk ________ which Jack is leaning is John’s．
