I was very happy to receive your letter of October 10th.我很高兴收到你10月10日的来信。

　　Thank you for writing to me.谢谢你给我写信。

　　Your letter came into my hand yesterday.我是昨天收到你的来信的。

　　It's a long time since I got your last letter.我收到你的信已经很长一段时间了。