It must be kept in mind that there is no secret of success but hard work.这句话中的that是什么成分?

题目

It must be kept in mind that there is no secret of success but hard work.这句话中的that是什么成分?

答案

that是主语从句的连接词
It （形式主语）must be kept （谓语）in mind （地点状语）that （主语从句的连接词）there is no secret of success but hard work.（後面全部是真正的主语）