She is just being polite

just放在系动词后 行为动词前

这么巧 今天讲课刚好讲这个 看下面：
The structure “be being + adjective / noun” is used to talk about action and behavior.

I was being very careful.
= I was doing something very carefully.

You're being stupid.
= You're doing stupid things.

上面你那句话的意思是 she is just doing sth. politely

她只是装着很礼貌。
就是只能放在这个位置啊.

如上所述。