你到那儿后给我写封信。
Drop me a line when you get there.
他偶尔给我写封信。
He sometimes writes to me.
给我们写封信，能收到你的信总是让人很高兴。
Drop us a line, it's always great to hear from you.
你可以给他打个电话或者给他写封信。
You can call him or write to him.
我买了这双鞋，这样我就可以在星期天给妈妈写封信了。
I bought this shoes, so I could print a bit of a letter to mother on Sunday.
那位老人要我替他写封信。
The old man asked me to write a letter for him.