关语从句This is one class you don't fall asleep in 1:you don't f

This is one class you don't fall asleep in
可以变为两个简单句：
This is one class,
In the class you don't fall asleep.
所以：
1.you don't fall asleep in是定语从句
2.省略掉的关系代词是that /which 在从句作in 的宾语
最后那个in 不能省略.理由从上面第二个句子可以看出来.从原句分析：
this （主语）is（连系动词） one class （表语）（相当于省略引导词 that,因为 that/which 在定语从句中做介词的宾语）you do not fall asleep in
3.这类从句用来修饰（名词）和（代词）

定语;that;名词，代词