主谓一致，即谓语动词在人称和数上要和主语保持一致。

  主谓一致包括语法一致、意义一致和就近一致。

  一、语法一致原则

  即在语法形式上取得一致，谓语动词的单复数形式由主语的单复数形式决定。

  一、单数名词、不可数名词、单个动词不定式短语、动名词短语以及句子作主语时，谓语动词要用单数形式。

  例：

  To see is to believe.

  眼见为实。

  Reading aloud is very important in learning English.

  学习英语时大声朗读非常重要。

  When they could finish the task is not known yet. 

  他们何时能完成任务还未知。

  Whoever wants to join in the competition is asked to sign his/her name here.

  要参加比赛的人请在这里签名。

  what引导的主语从句

  what引导的主语从句充当主语时，有时要以what所指代的词的意义来决定谓语动词的数。

  例：

  What he said is true.

  他所说的是真的。

  What we need are more volunteers. 

  我们所需要的是更多的志愿者。

  二、由连接词and或both … and连接的名词、动词不定式短语、动名词短语以及句子作主语时，谓语动词要用复数形式。

  例：

  What he said and what he did have greatly encouraged the other students.

  他说的话及行为极大地鼓舞了其他学生。

  Both his father and his mother are advanced workers.  

  他的爸爸和妈妈都是先进工作者。

  注意：有时，一些用and连接的主语表达的却是单数的概念，这时谓语动词也应用单数形式。

  1. 用and连接的名词表示同一人、同一物或同一概念作主语时；

  例：

  The secretary and manager was speaking at the meeting. 

  那位书记兼经理在会上讲话。

  2.“each/every/no/ many a  + 单数名词+ and + each/every/no/many a  + 单数名词”作主语时。

  例：

  Every hour and every minute is precious.

  每一小时，每一分钟，都很宝贵。

  三、 “名词+as well as, rather than, like, but, expect, besides, with, together with, along with, including, in addition to+ 名词”结构作主语时，谓语动词同第一个名词的数保持一致。

  例：

  Tom as well as two of his friends was invited to the party.

  汤姆以及他的两个朋友一起被邀请参加宴会了。