[填空题]

For what do people say "thank you" They say "thank you" for big favors as well as for ______ .

W：Excuse me, what did you say you would like to do, Mr Green
M: I said I’d better go hack to the hotel. I’m meeting someone this evening.
W: OK, how are you going hack By bus or taxi
M: I think I’d take a taxi. Do you know where I can get one
W: Oh, just wait by the roadside. I’ll wait with you.
M: OK, thanks. Are the taxis in London all black
W: Well, some of them are. Is this your first time in London
M: Yes, it is. Do you give extra money to the taxi drivers here
W: Oh, look. Here’s one. Taxi!
M: Thanks. See you tomorrow.

W: Excuse me, what did you say you would like to do, Mr Green
M: I said I’d better go back to the hotel. I’m meeting someone this evening.
W: OK, how are you going back By bus or taxi
M: I think I’d take a taxi. Do you know where I can get one
W: Oh, just wait by the roadside. I’ll wait with you.
M: OK, thanks. Are the taxis in London all black
W: Well, some of them are. Is this your first time in London
M: Yes, it is. Do you give extra money to the taxi drivers here
W: Oh, yes. Look, here’s one. Taxi!
M: Thanks. See you tomorrow.

What do you usually say to your new friend at the end of the conversation？
We tell him we are happy to（）him.