久仰!
I've heard so much about you.
好久不见了!
Long time no see.
辛苦了!
You've had a long day.You've had a long flight.
尊敬的朋友们!
Distinguished/Honorable/Respected friends
阁下(多用于称呼大使)
Your Excellency
我代表北京市政府欢迎各位朋友访问北京。
On behalf of the Beijing Municipal government, I wish to extend our warm welcome to the friends who have come to visit Beijing.
对您的大力协助,我谨代表北京市政府表示衷心的感谢。
On behalf of the Beijing Municipal government, i wish to express our heartfelt thanks to you for your gracious assistance.