主谓一致与常用句型

本节导读

主谓一致是指谓语动词在人称和数上要和主语保持一致。这看起来简单，但考试里有很多容易出错的情况：and 连接的主语什么时候看作单数，a number of 和 the number of 有什么区别，集体名词怎么处理。这一节还会讲 It 句型和 So do I 这类常用句型。

学完这一节，你应该能用三条原则判断谓语的单复数，会用 It is + 形容词 + to do 等句型，并能正确回应别人的话。

主谓一致的三条原则

1. 语法一致：主语是单数，谓语用单数；主语是复数，谓语用复数。
2. 意义一致：有些词形式是单数，但意思是复数（或者相反），谓语按意思处理。
3. 就近一致：谓语和离它最近的主语保持一致。

谓语用单数的情况

主语	例句
each, every, everyone, nobody 等不定代词	Everyone is here.
不定式、动名词、从句作主语	Swimming is good for your health. / What he said is true.
时间、金钱、距离作整体	Ten years is a long time.
the number of + 复数名词	The number of students is fifty.
news, physics, maths 等	No news is good news.

谓语用复数的情况

主语	例句
both, several, few, many	Both of them are right.
a number of + 复数名词	A number of students are late.
the + 形容词（指一类人）	The rich are not always happy.
police, people, cattle	The police are looking for him.
trousers, glasses, clothes	My glasses are broken.

注意区分 a number of（许多）和 the number of（……的数量）：前者当复数，后者当单数。

需要看情况的几种主语

and 连接的主语

and 连接两个主语，一般看作复数：Tom and Mary are friends. 但如果指的是同一个人或同一件事，或者前面有 each、every，就看作单数：

• Bread and butter is my usual breakfast.（面包和黄油是一份早餐）
• Every boy and girl has a book.（每个男孩和女孩都有一本书）

with 等词连接的主语

with、together with、as well as、except、besides、including 连接的短语，不改变主语的数，谓语只和前面的主语一致：

The teacher, together with his students, is going to the museum.
老师和他的学生们正要去博物馆。

or、either...or、neither...nor、not only...but also

这几个结构用就近原则。上一节讲过，这里再强调一遍：Either you or I am wrong.

集体名词和分数

family、class、team、group 这类集体名词，作为整体用单数，强调成员用复数：My family is big. My family are all well.

分数、百分数以及 some、most、half 等词后面有 of 短语时，谓语跟 of 后面的名词一致：Two thirds of the water is polluted. Two thirds of the students are girls.

It 句型

It 作形式主语

真正的主语是后面的不定式或从句，把它放到后面，用 it 占位：