她回信说她来不了。

She wrote back saying that she couldn't come.

《牛津词典》

他没有给她回信使她很恼怒。

She is annoyed that he has not answered her letter.

youdao

你给她回信了吗？

Have you answered her letter?

youdao

She would write back in a substantive way.

她的回信很冗长。

耶鲁公开课 - 1945年后的美国小说课程节选

Do you think I should neck or not? I shall not enter the kingdom of heaven anyway so I don't see what difference it makes.'" And then she writes back, Mary Brittle: "Dear Sabbath: Light necking is acceptable, but I think your real problem is one of adjustment to the modern world.

你认为我是该做还是不该做，我反正都上不了天堂了,因此，我认为做不做都无所谓，之后她给她回信了，玛丽-巴瑞特，亲爱的萨巴斯，你的做法是可接受的，但我认为,你真正的问题是无法融入现代社会。

耶鲁公开课 - 1945年后的美国小说课程节选