i read this on text. DBMS support database definition, data access, control of distributed databases and backup and administration. what situation that these roles important?

This is an academic question. I suggest you search the web for your answers.

Try search word "DBMS Fundamentals Concepts Administration"

I suggest that it really is an "academic" question and that perhaps the best thing is to do your own homework without simply fetching the answers off the Internet.

It's gonna be on the first exam, you know, and there you won't have an Internet connection.