This is the best book ____ on the subjectA.which there isB.that there isC.which isD.what is

This is the best book ____ on the subjectA.which there isB.that there isC.which isD.what is
This is the best book ____ on the subject
A.which there is
B.that there is
C.which is
D.what is

This is the best book ____ on the subjectA.which there isB.that there isC.which isD.what is
选 B,意思是,这是该主题的现有的最好书籍.
这是一个定语从句,然后从句里是个存现句,要有there be 句型
你一定以为是这样的：this is the best book that is on the subject
那么 on the subject 成了表语了,事实上他要做定语
that there is 这个定语从句,that 做主语,there做宾语,on the subject 做定语,就解决了问题

定语从句，应当填 C.which is , 这个句子的意思是：这是一本这个学科中最好的书。

D
前面先行词为books，是指物，可用which或that，但是因为有best 修饰，所以只能用that
出现one of +复数 这样的结构，如果one的前面没有其他的修饰限定词，则先行词确定为of后面的复数名词
希望对你能有所帮助。