I'm so tired that I think i could sleep a year.是什么从句?

I'm so tired that I think i could sleep a year.是什么从句?
I'm so tired that I think i could sleep a year.是什么从句?

I'm so tired that I think i could sleep a year.是什么从句?
我是如此的累以至于我想我可以睡一年.
i am so tired为主句
that i could sleep a year 为结果状语从句

so that 如此。。。以至于 结果状语从句

如果一定是从句,就是表语从句

结果状语从句。
so...that 引导结果状语从句