which one is correct?
I`m studying at a school

I`m studying in a school

I`m studying at school

I`m studying in school

Thanks in advance;)

Question

which one is correct?
I`m studying at a school

I`m studying in a school

I`m studying at school

I`m studying in school

Thanks in advance;)

Answer

i think "I`m studying at school" is the correct one.

Answer

I`m studying at a school ---incorrect

I`m studying in a school----incorrect

I`m studying at school
I`m studying in school 
These sentences would be correct but they need an object.
"I'm studying English in school."
"I'm studing English at school."
--How are you learning English?"
--I'm studying it in/at school.