You letter came to me this morning.
I have received your letter of July the 20th.
I’m writing to you about the lecture to be given next Monday.
I’m writing to ask if you can come next week.
How time flies! It’s three months since I saw you last.
Thank you for your letter.
In reply to your letter about (the exhibition this year)…;
Let me tell you that…
Please remember me to your whole family.
Give my best regards (wishes) to your mother.
Wish you a pleasant journey.
Wish you success. Wish you the best of health. (luck)
Looking forward to your next visit to China.
Looking forward to the pleasure of meeting you.
Expecting to hear from you as soon as possible.