A: May I come in?
B: What's up?
A: I'm sorry to disturb you, sir.May I dean your room now?
B: Well, I'm a bit tied up at the moment.
A: Shall I come back later, sir?
What time would you like me tc come back?
B: An hour later.
（an hour later）
A: The room has been cleaned already.
B: I'm satisfied with your work.
A: It's my pleasure. Your flask is empty. I'll go and get you another full one at once.
B: Please, wait a minute.
A: What's wrong, sir?
B: Could you change my bed sheets,please?
A: OK.
B: This is your tip.
