主语不是一个词而是一个句子，它因为有这个主句了，所以主语这个句子叫从句。主语从句可以位于句首，也可以位于句子的尾部，而在句首一般用it做它的形式主语，引导主语从句的关连有that和whether
这两个都是不能省略的。
What she did is not yet know.
It is certain that we shell be late.
It is curt to him that he had forgot to buy the book.
How the prisoner is escape is a complete secret.
1. ______ at the meeting yesterday is of great importance to the development of our business.
A. That we discussed B. What we discussed
C. How did we discuss D. What did we discuss
答案 B
(be of importance= be important)
2. _______ you say now can't make up for what you've done.
A. No matter B. Whatever C. However D. That
make up for 为……补偿
答案 B
3. _______ was once regarded as impossible has now become a reality.
A. That B. Which C. Who D. What
答案 D
4. _______ you do， do it well.
A. What B. Which C. That D. Whatever
which不能引导主语从句。
whatever=no matter what
答案 D
5. __________ the prisoner escaped is a mystery.
A. What B. How C. That D. Which
引导主语从句的关联词是that，whether和疑问词。
答案 B
一级建造师二级建造师消防工程师造价工程师土建职称公路检测工程师建筑八大员注册建筑师二级造价师监理工程师咨询工程师房地产估价师 城乡规划师结构工程师岩土工程师安全工程师设备监理师环境影响评价土地登记代理公路造价师公路监理师化工工程师暖通工程师给排水工程师计量工程师