1. That you are beautiful is true.

2. My opinion is that you should not go alone.

3. The reason that he didn't come is clear.

4. I say that I know it.

5. The great thing about a computer notebook is that no matter how much you stuff into it, it doesn't get bigger or heavier.

有的人说前三句的主句就是全句，第五句 no matter how much you stuff into it 做的是宾语从句的状语，那主句不就是The great thing about a computer notebook is？

第四句I say 是宾语从句主句，但是I say 不是一个句子，怎么能当主句呢？