3.there be存在句的谓语动词可以与情态动词连用

there be存在句的谓语动词有时可以与情态动词连用。

There must be some terrible mistakes．(人教大纲版高三第62页)

大概出了什么大差错了。

There could be as many as six hundred thousand sheep fed within six miles of Salisbury，measuring every way round and the town in the centre．(人教大纲版高二上第39页)

在以索尔兹伯里为中心的方圆六英里内，养有多达六十万只羊。

There must have been a fight between the boys last night．

昨晚这两个男孩准是打了架。

There can't have been much traffic so late at night．

那么晚车辆不可能很多。

There used to be many different species of rhinos，including one that was six met res high and nine met res long!(人教大纲版高一上第143页)

以前有很多种犀牛，其中有一种六米高，九米长。