What’s the difference between “the same as “and “the same that “
There is an incomplete sentence that “This pan is the same ___I bought yesterday.”

My teacher said the word should be “as”,but why can’t I use the word “that “?

Please help me!!!

Question

What’s the difference between “the same as “and “the same that “
There is an incomplete sentence  that “This pan is the same ___I bought yesterday.”

My teacher said the word should be “as”,but why can’t I use the word “that “?

Please help me!!!

Answer

Actually  the proper sentence is:
This pan is the same AS THE ONE THAT I bought yesterday.
When you use "same as", it should be followed by a noun phrase (This pan is the same as THAT PAN.)or a pronoun (My bag is the same as yours.) that you are comparing the subject to.

Answer

The missing phrase is 'as the one'
"This pan is the same as the one I bought yesterday."

Just saying 'as' is correct, but a little less clear to the listener. The listener will ask themself - 'Same as what ??" and use the context of the preceding conversation to understand.  I would always use 'as the one' myself to make it clearer.