there be 句型 的反意疑问句为什么

there be 是“有”的意思,一般指“某地有什么东西”,表示“存在的有”.有各种时态的变化,如：
There is a book on the desk,isn't there?
There isn't a book on the desk,is there?
There used to be a temple here,didn't there?
There will be NO class this afternoon,will there?
There has been an accident,hasn't there?