Question

What kind of books in the library? 这句话有错吗？

Answer 1

有问题。
我们从语法上来分析：疑问句都是从陈述句转变过来的。比如，陈述句：They are in the library.他们在图书馆。可以转变为疑问句：Who are in the library?谁在图书馆？或Where are they?他们在哪里？（这两个疑问句只是提问的对象不同，第一个针对陈述句中的they，第二句针对陈述句中的in the library）
而你的这句话陈述句应该是：There are all kinds of books in the library.图书馆里有各种各样的书。或者There are novels and books on sciences,society,daily life,etc. in the library.图书馆里有小说和关于科技、社会、日常生活等的书。
你的这个问句是针对书的种类，即all kinds of books 或者novels and books on sciences, society, daily life,etc.，这样的话，转换过来就是：
What kinds of books are there in the library?
所以问题就是句子中缺了are there

Answer 2

有错，没有谓语，可改成;
What kinds of books are in the library?

Answer 3

What kind of books is in the library?缺少动词

Answer 4

有，缺少谓语动词。
What kind of books are in the library?

Answer 5

What kind of books can you find in the library?

Answer 6

对