M3U3 Back to the past学案
Grammar and usage
第一部分：重点讲解
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
