Question

___ in the regulations is that you ___ other people the password of your e-mail account．    
A．What is required; not tell              B As is required; shouldn't tell
C．It is required; not tell                D．It requires; shouldn't tell

Answer 1

A

试题分析：句意：在制度中你所被要求的就是你不应该告诉别人你的邮件密码。what为所字机构，作为主句的主语，即为主语从句，is之后为表语从句，句中有require要求，表语从句用虚拟语气should +动词原形，should可以省略，故选A
点评：名词性从句分为主语、宾语、表语、同位语从句四种，同位语从句和定语从句的区别在于：that作为关系代词，可以引导定语从句，充当句子成分，在从句中作宾语时可以省略； that引导同位语从句时，起连词的作用，没有实际意义，不充当句子成分，一般不能省略。
试比较下面两个例句:
I had no idea that you were here．（that引导同位语从句，不能省略）
Have you got the idea（that）this book gives you of life in ancient Greece？（that引导定语从句，作宾语，可以省略）