Is this book _____ you borrowed from the school library?A th

1.答案：A the one.
2.
1）这样的题目,需要把它变成陈述句就很简单了：
A：This book is the one (that) you borrowed from the school library.
B：This book is that you borrowed from the school library.
2）如果选B that
理解成表语从句的话,则表语从句中borrowed后面缺少宾语,所以必须用what来引导,因为that引导的表语从句时,that不能在从句中充当任何成分,只起引导作用.
理解成定语从句的话,则主句This book is不完整,它缺少表语（先行词）,也就是说定语从句that you borrowed from the school library所修饰的对象都没有.
3）选A the one = the book,主句This book is the one完整.
而定语从句you borrowed from the school library修饰先行词the one,且关系代词代替the one,在定语从句中充当borrowed的宾语,所以关系代词可以省略.

A the one
the one 除了做表语外，还兼做后面定语从句的先行词。而that是不能做先行词的。

A你把句子还原一下成陈述句，this is book __ u ...如果你用that book 前面应该有个a或the但是没有，应该用the one 表特指作代词代book形成一个定语从句。

A、B都可以，用改成陈述句的方法：A：This book is the one......：主句完整
B：This is the book ....：主句亦完整

A.the one
the one 表示特指

A

答案A，表特指
B项是干扰项，似乎为定语从句的连接词，但是这句不能构成定语从句，似乎有先行词book ，但是定语从句的原则是从句的内容修饰说明先行词，而这里缺的是一个特指，应先补充完整特指再用定语从句，所以选A！