there be 句型中+动词的现在分析形式,那还要加be动词吗?

问题描述:

there be 句型中+动词的现在分析形式,那还要加be动词吗?
There's an old man ______ on the road
应该填is lying 还是 lying?

There be中的be可以是is are ,而这个例句中已经有了be动词了,There‘s就是There is