精选优质文档-倾情为你奉上名词性从句 主语从句、表语从句、宾语从句和同位语从句在复合句中的作用相当于名词，因此这种从句叫名词性从句。（一）主语从句主语从句是在复合句中充当主语的从句。一. that引导的主语从句that 引导主语从句时，that不做成分，也没有意义，但不能省略。that引导的主语从句可用形式主语it代替，而把that从句置于句尾。That light travels in straight lines is known to all.众所周知，光沿直线传播。可转换为：Its known to all that light travels in straight lines.it用作形式主语，代替主语从句的句型。it+be+形容词+主语从句（这类形容词有 probable ,evident ,likely, possible ,important, necessary ）It is certain that free medical care will be given to most people in
