an

音标发音

通常来说，a 是用在以辅音开首的词前面，an 是用在以元音开首的词前面；
可数名词前面用 a（或 an），不可数名词前面不可用a（或 an)，如可以说 a healthy boy，却不可以说 a health；
在特定情况下，a（或 an）可以用在复数形式前面:习语中有a few (books)，a great many (books)等表示方法。在表示时间或款项的短语前面，如 a further five minutes。在若干在形式上是复数而在意思上是单数的单词前面，如 a barracks，a links。在美国口语中，如 a good ways，a long ways；
a （或 an）有时有“一个而不是那所要的一个”的意思。I got a letter indeed，but it was from a friend. 事实上，我收到了一封信，但只是一个朋友的来信。
a 也有“任何一个”的意思。I wanted to read a book，I did not care whether it was a history，a novel，or a biography.
a 与 few 搭配使用时，few 是“很少”，有“几乎没有”的意思。a few 是“若干”，有“颇有几个”的意思。注意，only a few 却等于 few，也是“很少”的意思。

Beauty is an attitude. It has nothing to do with age.
美是一种态度，与年龄无关。
Good luck is when an opportunity comes along and you're prepared for it.
好运就是当机会来临时，你早已做好了准备。
An attempt by anti-abortionists to tighten the rules was defeated.
反堕胎者所作的加强法规的尝试失败了。
The driveway makes a hook around an old tree.
车道绕过一棵老树来了个急转弯.
Television allows viewers to experience an event without any loss of immediacy.
电视让观众可以即时经历某一事件.

An is used instead of "a," the indefinite article, in front of words that begin with vowel sounds. (a)
&rarran obsolete or dialect word for if
Netherlands Antilles