以书信形式
identified by a letter───用字母识别
by letter or telegram───通过信件或电报
letter───n.信；字母，文字；证书；文学，学问；字面意义；n.（Letter）（美、英、巴西）莱特（人名）；vi.写印刷体字母；vt.写字母于
purloined letter───被盗信
letter to───发往……的信
letter name───字母名称
farewell letter───告别信
nasty letter───讨厌的信
drop letter───同一邮局所收发的信；<美>托人由一地带到另一地付邮的信件
I will contact you by letter.───我会给你写信联系的。
Your job is to group them by letter and put them in numerical order.───你的工作是把它们按字母编组，再把它们按数字顺序排序。
You will be notified by letter.───将用信函通知你。
I shall bring it to you myself without waiting, and letter by letter help you to read my writing.───我立刻就自己送来给你，而且一个字母，一个字母地帮助你读。
It is often cheaper(though less quick)to send catalogues through the mail as (photocopy )instead of by letter post.───用影印的形式通过邮件传送目录比寄信常常要便宜，尽管要慢一些。
We stayed in touch by letter but had not seen one another in years, and now Odette was dead.───多年来，虽然再也未曾谋面，我们一直保持着书信往来。奥黛特已经去世。
We have talked about this matter by letter, and have decided to begin an official negotiation next month.───我们已经就此事进行函洽，并约定下月开始正式谈判。
The tender must be confirmed promptly by letter or by the despatch of a signed copy of the telex, telegram or facsimile.───投标必须立即用信件或通过电传、电报或传真的签署副本加以确认。
"But when you get down to brass tacks, " I interrupted, "the comparison is still a less-than comparison letter by letter. "───“但是本质上，”我打断了Guru，“比较函数还是从字面上的‘小于‘比较。”