复信的英文：
give a reply
write back

参考例句：

Kindly favour us with an early reply
请早日复信(常用于商业信件)。

I didn't receive an acknowledgement of my application.
对我的申请，我还没有收到复信告知收悉。

I have to apologize for not answering your letter in time
我没有及早复信，请原谅(迟复为歉)

This year I have been particularly fortunate in receiving an unusually large number of rejection letters.
今年我已经够幸运的了，收到了大拒绝的回复信。

He wrote a terse reply to Rhoda, sealed it up, and tossed it in his outbasket
他写了一封简明扼要的复信给罗达，封起来，扔在发文的信筐里。

In electronics,the process of synchronizing a repetitive signal source with timing signals.
在电子技术中，使一重复信号源与同步[定时]信号同步的处理方法。参阅clock。

give是什么意思：
n. 弹性，伸展性
v. 给；授予；赠送；捐赠；供给；告诉，提供；产生；让步；塌下；举办；支付

Will you give it a shot?
你想做尝试吗？

He gives twice who gives quickly

The purpose is not to give an exhaustive treatment.
其目的并不是给出全面彻底的处理。

reply是什么意思：
v. 回应，答复，做出反应
n. 回答，答复

Reply to the sender and all the recipients Reply to the sender and all the recipients Reply All
回复发件人和所有收件人，回复发件人和所有收件人，回复全部

Post reply to the Newsgroup and mail a reply to the author
将回复消息投递到新闻组并向作者回复一个邮件

His challenge draws no reply.
他的挑战没有引出回答。

write是什么意思：
v. 写；写作，作曲；写信

By writing you learn to write
从写作中学写作

legible writing
字迹清楚的书写

Start out to write/with the intention of writing a novel
动笔[想]写一部长篇小说.