a (an)/one.导航词义：一个

1. a (an):indef. art. 一个.通常用于单数可数名词之前，泛指某类人或事物中的一个。

My friend needs a bilingual dictionary.

我的朋友需要一本双语词典。

Would you like a sandwich?

要来份三明治吗？

There is a bird sitting in the tree.

树上卧着一只鸟。

2. one:num. 一，一个.强调数量的概念，说明是一个而不是两个或三个。

One million means a lot to me.

一百万对我来说是个大数目。

Plant one tree per hour.

每小时种一棵树。

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1·A gang taunted a disabled man.

一帮混混儿羞辱了一个残疾人。《柯林斯英汉双解大词典》

2·She's a singer with a band.

她是一个乐队的歌手。《牛津词典》

3·They had a butler, a cook, and a maid.

他们有一位管家、一位厨师和一位女仆。《柯林斯英汉双解大词典》

4·Ha! It was a cross between a laugh and a bark.

“哈！”那是一种一半是笑一半是厉声喊叫的混杂声。《柯林斯英汉双解大词典》

5·A man in a crash helmet was mounting a motorcycle.

一个戴着防撞头盔的男子正骑上一辆摩托车。《柯林斯英汉双解大词典》

6·For a year I dated a woman who was a research assistant.

有一年的时间，我一直和一个女助理研究员约会。《柯林斯英汉双解大词典》

7·Nothing gives a room a faster facelift than a coat of paint.

没有什么比一层油漆能更快地使房间面貌一新。《柯林斯英汉双解大词典》

8·A schoolgirl rushed into a burning apartment to save a man's life.

一名女学童冲进一栋着火的公寓去救一个男子的命。《柯林斯英汉双解大词典》

9·He's a nut, a real character.

他是个怪人，一个真正与众不同的人。《柯林斯英汉双解大词典》

10·A lion is a dangerous animal.

狮子是猛兽。《牛津词典》