They don’t seem to answer the phone.---
There isn’t anyone at home,is there?
意思是,家里没有人,是吗?
anyone在此是someone的否定句中的转换
There be 句型中,反义疑问部分必须为 be(n't)+ there
例如：
There is a beautiful girl in the garden,isn’t there?
There are some apples in the basket,aren't there?
当陈述部分有never,seldom,hardly,few,little,barely,scarcely,nothing 等否定意义的词时,后面的反意疑问句则为肯定形式：
There are few apples in the basket,are there?
There isn't any milk left,is there?