____is expected,according to the survey ,that ho

It is expected, according to the survey ,that housing price can not go up any more.
根据调查,预计房价不会再往上涨了.
这句话中according to the survey是插入语,起到补充说明的作用,主句是It is expected that……
类似的还有,It is well known that...那As是用什么句式呢？as可以引导状语从句和定语从句，例如：
As she is a model teacher, she gives a good example to others.（as引导原因状语从句）
I saw him as he was getting off the bus. （as引导时间状语从句）
As is reported in the newspapers, talks between the two countries are making progress. （as引导定语从句）那这一句是什么句式？It is expected, according to the survey ,that housing price can not go up any more.

这是主语从句，it是形式主语，真正的主语是that引导的从句。