there be 结构的附加疑问句部分要用什么来充当主语

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?我相信你现在懂了。、、