There are all kinds of key: big, small, heavy, light, decorated, plain, silvery, golden, tin, copper, etc. It is amazing how each key works according to the teeth shape they carry. Sometimes, two keys look so alike, one can open a door, the other just can't.
In my school, there is a kind of key called master key, that can open all doors in a certain building. I used to have one to open any classroom. It is cool. I don't have to get a cusdodian to open the classroom for me. But, who knows when, new locks were installed to all classrooms after we returned to school after one summer. The master key was no longer a master. I didn't expect It reached its retirement so soon.
Everyone was given a key with a mark of "x" in school. People called it "pass" key. Any key is supposed to get you pass a door to another space. So why it got the special name, I had no idea. Anyway, the pass key didn't work like the master key. It didn't open any door you want to open. It is not for the office, it is not for the classrooms, either. It only gets you to men's room, lady's room, and teachers' lundge (?). That's why everyone needs it.
