Question

高中语法（从句） Professer Lee's book will show you_can be used in other fields.

Answer 1

Professer Lee's book will show you that you have observed can be used in other fields.
李教授的书会告诉你，你所观察到的东西可以用在别的领域
选A

这里的that不是类似于I can tell you that或I can show you that中的that
你可以把that you have observed替换成the things that you have observed，只是the things 省略了而已.
把that you have observed 看做一个整体，这个整体其实是can be uesd...这半句的主语
that you have observed表示你所观察到的东西，you have observed 修饰that，很久不想语法了，可能是同位语吧
如果还原全句，就是Professer Lee's book will show you (that) that you have observed can be used in other fields. 容易混淆的是两个that是不一样的用法
也可以用what替代you前面的that
Professer Lee's book will show you (that) what you have observed can be used in other fields.