英语语法高手请帮我分析这句话

来源:百度知道 编辑:UC知道 时间:2024/05/21 17:02:20
As ( ) announced in today's papers, the Shanghai Export Commodities Fair is also open on Sunday.
A.being B.is C.to be D.been
为什么选B不选A?请说详细点,谢谢!

这是一固定用法。此句中As引导的句子为非限制性定语从句的倒装句,对后面的主句进行修饰。
类似的结构还有: As is said above
As is reported above等