used for writing the sound that people make when they are thinking about what to say next, or when they are not sure how someone will react to what they are going to say 哦,嗯,呃(表示谈话人思考或犹豫时发出的声音)
The airport has one of those, um, travolators. 机场有一条那种,嗯,自动人行道。
‘What time will you be back?' ‘Um, I'm not really sure.' “你什么时候回来?”“嗯,我真的说不准。”