Nothing is more certain than that every trace of Hilter'sfootsteps,every stain of his infected and corroding fingers, will be spongedand purged and, if need be, blasted from the surface of the earth.
请教that有哪些用途和成分，是引导主语从句吗？
《牛津英语使用方法指南》中文版第 4 版第 525 页：than 可以代替补语（即传统语法中的表语），书中称 than 非常像关系代词，潜台词就是说不是关系代词。该书中例句：She was more frightened than I was. was 可省略，省后按《韦氏词典》说法，略正式。Nothing is more certain than that every trace of Hilter's footsteps, every stain of his infected and corroding fingers, will be sponged and purged and, if need be, blasted from the surface of the earth. 可知 that 引导的从句是主语从句，比较状语从句的句尾省略了 is。另外，will 前逗号应该去掉，搜了下Google，有些版本就无逗号。
按现代语法剖析，more certain 是比较项，比较对应项在比较分句中作主语补足语，不可以出现，故形成空位（gap），这个空位不能文字补全。
再来个相同结构的例句：Nothing is more dangerous than that you make friends with him. 其中的 that you make friends with him 就是主语从句，其中用了虚拟语气。
