Question

There is nothing in the books， is there？

为什么填 Is there.
又什么时候填 Isn't there.

Answer 1

因为陈述句部分是否定含义，所以反义疑问部分要用肯定疑问来表达。若把句子前半部分改为：There is something in the books，那么反义疑问部分就是isn't there。

Answer 2

答：There is nothing in the books， is there？（书上什么都没有，是吗？）前面的陈述部分含有否定词nothing,是表示否定意义的,所以说后面的反意疑问句的简略问句一个是有肯定形式的。例如：

There is something new in today's newspaper， isn't there？