There is no such thing on the second floor of Nanning City. There is a grammatical error in the second sentence, so I won't explain it.
On the third floor, I didn't ask you to answer Nanning, the capital of Guangxi.
On the fourth floor, you should use in. He goes to school instead of working.
So, the correct answer is as follows
I live in Nanning, Guangxi. I live in Nanning, Guangxi.
I study in Minle Road Primary School. I study in Minle Road Primary School.