Dear Dr. Zhang
I wrote to thank you for the great work because I finally received the green card 13 days ago. I wanted to write to you earlier but I had tavelled for a conference. Thanks for your knowledge and experience that made the difference. I hope to work wth you again because I may need to do some immigration related procedures, including bringing my brothers here. I may come back with a few questions aswell.
Best regards,
Client03/25/2014