there is +adj.和 it is +adj.怎么区分?

题目

there is +adj.和 it is +adj.怎么区分?
如题
例：__is no possibility__Bob can win the first prize in the match (正解：there;that)
it;that
以此为例教教我吧,
不是adj 看错 囧

答案

there is +名词,that从句是possibility的同位语 如果是It is possible(形容词) that...则it 是形式主语,that从句是真正的主语,即That ...is possible.