Yesterday our chemistry teacher teacher asked so difficult a question ( )puzzled all of us.

Yesterday our chemistry teacher teacher asked so difficult a question _____puzzled all of us.
Yesterday our chemistry teacher asked so difficult a question ________ it puzzled all of us.
分别填什么？为什么？

1、which 或者 what
which (what) 作为从句的主语，整个从句which(what) puzzled all of us 修饰 question的
2、that
分析从句 主谓宾齐全，而且so .......that.... 一般作为固定用法，翻译为 太....以至于.....
so beauiful a girl that everyone can't help looking at her, 那女孩太漂亮了，以至于每个人都忍不住看着她。

Which That 语法详细就不讲了，说个最简单的方法，把整个句子缩写，主谓宾（主系表)结构，第一句是一个完整的一个句子，它要一个修饰代词，第二句是完整的两个句子，所以中间要一个普通连接词就可以啦。 这是个人总结的经验，可以试试类似的题目，希望对你有帮助。

1.which 2.that which 引导主语从句， so...that 是如此...以致于 固定搭配

你好！ 1. which (定语从句句式，which=question) 2. that (结果状语从句句式，so...that...，如此……以至于……） 仅代表个人观点，不喜勿喷，谢谢。