【正确答案】Dear Jack,
I am writing to thank you for all the help you gave us in moving into our mew flat. As you know, my mother is in poor health and there is a lot of furniture. I know we would never have been able to move all the things into the new flat without your help. I am arranging a housewarming party soon and I am looking forward to seeing you then. Thank you again for everything you have done for us.
Yours,
Liu Ming