在英语句子里，谓语受主语支配，其动词必须和主语在人称和数上保持一致，这就叫主谓一致。寻其规律，大致可归纳为三个原则，即语法一致、逻辑意义一致和就近一致原则。
（一）语法一致原则：语法上一致就是谓语动词和主语在单、复数形式上保持一致。
1、以单数名词或代词、动词不定式短语、动名词短语或从句作主语时，谓语动词一般用单数形式；主语为复数时，谓语动词用复数形式。如：his father is working on the farm. / to study english well is not easy. / what he said is very important for us all. / the children were in the classroom two hours ago. / reading in the sun is bad for your eyes.
注意：由what引导的主语从句，后面的谓语动词多数情况用单数形式，但若表语是复数或what从句是一个带有复数意义的并列结构时，主句的谓语动词用复数形式。如：what i bought were three english books. / what i say and do is (are) helpful to you.
2、由连接词and或both … and连接起来的合成主语后面，要用复数形式的谓语动词。如：lucy and lily are twins. / she and i are classmates. / the boy and the girl were surprised when they heard the news. / both she and he are young pioneers.
注意：① 若and所连接的两个词是指同一个人或物时，它后面的谓语动词就应用单数形式。如：the writer and artist has come.; / ② 由and连接的并列单数主语前如果分别有no, each, every more than a (an) , many a (an)修饰时，其谓语动词要用单数形式。如：every student and every teacher was in the room.. / no boy and no girl likes it.
3、主语为单数名词或代词，尽管后面跟有with, together with, except, but, like, as well as, rather than, more than, no less than, besides, including等引起的短语，谓语动词仍用单数形式；若主语为复数，谓语用复数形式。如：mr green, together with his wife and children, has come to china. / nobody but jim and mike was on the playground. / she, like you and tom, is very tall.
4、either, neither, each, every 或no +单数名词和由some, any, no, every构成的复合不定代词，都作单数看待。如：each of us has a new book. / everything around us is matter.
注意：① 在口语中当either或neither后跟有“of+复数名词（或代词）”作主语时，其谓语动词也可用复数。如：neither of the texts is (are) interesting. ② 若none of后面的名词是不可数名词，它的谓语动词就要用单数；若它后面的名词是复数，它的谓语动词用单数或复数都可以。如：none of us has (have) been to america.
5、在定语从句时，关系代词that, who, which等作主语时，其谓语动词的数应与句中先行词的数一致。如：he is one of my friends who are working hard. / he is the only one of my friends who is working hard.
6、如果集体名词指的是整个集体，它的谓语动词用单数；如果它指集体的成员，其谓语动词就用复数形式。这些词有family, class, crowd, committee, population, audience等。如：class four is on the third floor. / class four are unable to agree upon a monitor.
