letter;mail;missive;correspondence ;
例句:
The letters might not have been meant for me at all.
这些信件可能原本就不是写给我的。
Here's another selection of recent letters from our postbag.
这是我们从近期公众来信里挑选出的又一批信件。
People hold onto letters for years and years.
人们经年累月地保存着信件。