A.Korea made food --> Korean food is good.

=> Corrected: The sentence is corrected grammatically.

B. He work is post ofice. --> He works at the post office.

=> Corrected: The sentence is corrected grammatically.​

Ah,okay. (Correct)

Mom, What is post post ofice. --> Mom, what building is this?

=> Corrected: The sentence is corrected grammatically.​​