求助一道高一英语（必修1）

题目

求助一道高一英语（必修1）
在下列定语从句中,用适当的介词填空.
1.He built a telescope___which he could study the skies.
2.The desk____which Jack is leaning is John's.
3.He bought a book yesterday,the author____which is a teacher.

答案

1 through
2 upon
3.of
都是定语从句.介词前置 through a telescope
lean upon the desk
author of the book