If the door open on an invitation means that, at this time can be gently knock on the door of the office to show respect for the masters, and then will naturally be welcomed.

假如门敞开着就意味着一种邀请，这时便可以轻轻拍门以示对办公室主人的尊重，随后就会天然而然受到欢迎。

youdao

5 out of the room courtesy: enter the room, gently knock on the door first, to hear response to Progressive.

5出入房间的礼貌：进入房间，要先轻轻敲门，听到应答再进。

youdao