You’ve had a long day. You’ve had a long flight.辛苦了！
Yes,I understand. 是的，我明白了。
Thank you very much. 非常感谢。
Thank you so much for coming.感谢光临！
Take care!多保重！
Stand up,please. 请站起来。
Open your book,please. 请把书打开。
Long time no see.好久不见了！
Let me help you. 我来帮助你。
It’s very kind of you! 你真是太好了。