the same...as,the same ...that,such .as定语从句有何区别?

题目

the same...as,the same ...that,such .as定语从句有何区别?
如：1.This is the same pen as I lost last week.
2.This is the same pen that I lost last week.
3.This is such a pen as I lost last week.
句1意为这和我上周掉的那支笔一样,句2意为这就是我上周掉的那支笔,那么句3和句1有何区别呢?

答案