单数与复数

由两个对称部分组成的东西，即使只有一件，也用复数名词和复数动词：trousers, jeans, shorts, pyjamas, glasses, sunglasses, scissors, headphones。要数它们，就用 a pair of / two pairs of。

• These jeans are too tight.

  这条牛仔裤太紧了。（不说：is）

• Where are my glasses? I can't find them.

  我的眼镜在哪儿？我找不到了。

• I bought a pair of shorts and two pairs of socks.

  我买了一条短裤和两双袜子。

• This pair of scissors is really sharp.

  这把剪刀非常锋利。（主语是 pair → 用 is）

💡中文说“一条裤子”“一副眼镜”，把它们当成一件东西，所以学习者常写出 a jeans 或 my glasses is。在英语里，这些词没有单数形式——要用 a pair of 或 some：I need some new glasses / a new pair of glasses.

• news 是不可数名词：The news is good. 一条消息说 a piece of news（不说：a news）。
• 以 -ics 结尾的学科和领域：maths (AmE: math), physics, economics, politics, athletics, gymnastics → 动词用单数：Physics is hard.（politics 表示“某人的政治观点”时，可以用复数。）
• means, series, species 单复数同形：a TV series → two TV series；a means of transport → many means of transport。

• The news is on at seven.

  新闻七点播出。

• I have some good news for you.

  我有个好消息要告诉你。（不说：a good news）

• Economics is my favourite subject.

  经济学是我最喜欢的科目。

• This drama series is very popular in Vietnam.

  这部电视剧在越南很受欢迎。

family, team, staff, government, company, class, audience, committee 指的是一群人。在英式英语中，动词可以用单数（把整个群体看作一个整体），也可以用复数（看作其中的各个成员）。美式英语通常用单数。

police 和 people 总是用复数动词。指一个人时说 a police officer、a person（不说：a police）。person 的常用复数是 people；persons 只出现在正式文本中（告示、法律）。

• The team is / are training hard for the final.

  球队正在为决赛刻苦训练。（英式：两种都可以；美式：用 is）

• The police are looking for the driver.

  警察正在寻找那名司机。（不说：is）

• Her brother is a police officer.

  她哥哥是一名警察。

• There were a lot of people at the market.

  市场上有很多人。

💡一旦选定了单数或复数，整句话就要保持一致：The team is happy with its result / The team are happy with their result.

把一笔钱、一段时间或一段距离看作一个总量时，即使名词带 -s，动词也用单数。

• Two hundred dollars is a lot for a pair of shoes.

  一双鞋两百美元可不便宜。（不说：are）

• Three years is a long time to wait.

  等三年可是很长的时间。

• Five kilometres isn't far. Let's walk.

  五公里不远，我们走路去吧。

但如果想的是一个个单位逐一过去，用复数动词依然很自然：Ten years have passed since we left school.

• ✗My new jeans is too long.

  ✓My new jeans are too long.

  jeans 是复数名词。

• ✗I need a new trouser.

  ✓I need new trousers / a new pair of trousers.

  没有单数形式；用 a pair of。

• ✗The news are very bad today.

  ✓The news is very bad today.

  news 是不可数名词。

• ✗The police is coming.

  ✓The police are coming.

  police 总是用复数动词。

• ✗There were many persons at the party.

  ✓There were many people at the party.

  person 的常用复数是 people。

• ✗Physics are difficult.

  ✓Physics is difficult.

  以 -ics 结尾的学科 → 用单数。