高中状语从句When you read the book,you'd better make a mark __you have any questions.

问题描述:

高中状语从句When you read the book,you'd better make a mark __you have any questions.
为何空格处填where而不是at which?

亲 这是状语从句 只有在定语从句中 你的说法才成立 这道题就是考这个