Question

there have been 的用法

there be 是有什么什么。
have been是完成时。
求分析there have been

Answer 1

there be句型是倒装句，意思是"有"，be的形式由be后第一个名词的单复数决定；
there have been，意思是"曾经有"，是there be句型的现在完成时态形式，此时be后主语为复数名词，如果be后主语为单数名词，则应为there has been
如
There have been some encouraging signs over the past couple of months.
在过去的几个月里有一些令人鼓舞的迹象。
There has been a singer playing guitar at the bar for many months.
曾经有个歌手在酒吧里弹了几个月吉他。

Answer 2

there have been 是已经存在某个东西
比如 ：there is a river here, 这有一条河，
那么： there has been a river since 1993, 意思就是从1993年开始，这就有一条河了。

Answer 3

我个人觉得 不存在这个句型吧