(knock on door)
A：Hi Chen Hao, am I interrupting you?
A：I was afraid I might disturb you when I saw your door was shut.
A：It is good to have some privacy every now and then, especially when you need to concentrate on something, but I think you should reconsider keeping it shut all the time.
A：It can give a bad impression to your colleagues, some of whom don't have the luxury of an office with a door.
A：When people see your door shut, they assume that you are not to be disturbed. I was reluctant to knock, but I needed to deliver a report to you so I decided to take a chance.
A：A closed door implies that you might have someone in your office or that you are working on an important project and don't want to be disturbed. You might also be having a confidential phone conversation and don't want to be overheard.
C：(To the co-worker) Todd, I am really disappointed in your work on this project. Please take it back and rework it using the correct data. Hi Amy, come in. Todd was just leaving.
A：Bye Todd, see you later. (Amy hesitates a minute) Gee, that was embarrassing.
A：Well, walking up while you were criticizing Todd was embarrassing, because I am sure that made him feel uncomfortable to have you reject his report and especially when other people walking by could hear your conversation with him.
A：You should have shut your door while you were talking to him so no one else would overhear you.
A：I did, but I didn't say that you should have it open all the time.
A：You needed to get up from your desk and shut the door. Or you could have asked Todd to close the door. Then you could have had your talk in private.