英语的一致关系有三种:主谓一致，代词一致，肯定与否定一致。
英语语法要求，主语如果是单数，谓语动词也要用单数形式;主语若是复数，谓语动词也要用复数形式
例如:
She likes to eat well.她好吃
We all like good food.我们都喜欢好饭菜。
Everybody was happy with the decision. 人人都对这个决定感到高兴。
I am a doctor.我是个医生。
(二)概念一致
1. And连接的两个或多个单数名词作主语时，谓语动词用复数形式
His opinion and mine are different他的观点和我的是不同的。
Bob and Peter are deadly rivals. Bob和peter是死对头。
What she says and what she does are totally different. 她说的和做的完全不同。
但是如果and连接的是指一个单一概念时，谓语动词用单数。
Bread and milk has been my breakfast for years. 牛奶面包多年来一直是我的早餐。
Her lawyer and old friend is going to marry her.她的律师和老朋友要娶她。
All this effort and sacrifice has come to nothing. 所有这些努力和牺牲都白费了。
由and连接的单数主语分别有many a，ever y，each，no修饰时，动词用单数。
如：During the holidays, every train and every plane was crowded.假期期间每列火车及每架飞机都非常拥挤。
No boy and no girl has the right to refuse education. 男孩和女孩都没有拒绝教育的权利。
Man a man and man a woman was moved b this picture。许多男男女女都被这幅画感动。
2.如果主语是一个抽象概念(如不定式、动名词、主语从句等)谓语动词用单数形式。如果主语是用and连接的两个或多个抽象概念，谓语动词用复数形式。
如：Swimming jogging and cycling are all goad farms of sports exercises.游泳、慢跑和骑自行车都是很好的运动形式。
To live to eat is not a very goad attitude toward life. 活着就是为了吃不是好的生活态度。
To live to eat and to eat to live are very different attitudes toward life.
以what，who，why，haw, whether等wh一词引起的从句做主语时，谓语动词通常用单数;由and连接的两个主句如果指两件事，动词用复数。
例如:What he is doing is not clear yet他在干什么还不清楚
What he is doing and whether I know him are two different things.他在干什么和我是否认识他是两件不同的事。
What she told me is none of your business. 她和我说的什么用不着你管。
What she told me and what she told you are totally different things.
以what从句为主语的“主一系一表SVC"句型中，如果主句的表语是复数，主句谓语动词用复数形式;what从句本身是复数意义，主句谓语动词也可用复数。
如：What I need buy now are four tea cups and a pair of sports shoes.
我需要买的是四只茶杯和一双运动鞋。
What were thought to be five dogs were actually five sheep.
被认为是五条狗的东西实际上是五只羊。
3.集体名词family，class，crew(全体船员或机组人员)，crowd, group, committee, audience, government, public, team, staff, population等做主语时，若作为一个整体看待，后面谓语动词用单数; 如就其中每一个成员来考虑时，则用复数。
例如: My family is a big one.我家人多。
My family are all music lovers. 我全家人都爱好音乐。
Eighty percent of China\' s population are peasants. 百分之八十的中国人口是农民。
China has a huge population. 中国有众多的人口。
The population of China is the largest in the world. 中国的人口是世界上最多的。
People, police, cattle,(牛)，militia(民兵)，poultry(家禽)，vermin(害出)等作主语时，后面的动词要用复数。
4.不定代词either，neither，ever y，each，one，the other, another以及所有的复合不定代词作主语时，谓语动词只用单数，包括“every/each/no……and every/each/no……”作主语时。
如：Every/Each plane and every/each pilot is ready to take off.
每架飞机和每个飞行员都已准备好起飞。
No plane and no pilot is ready to take off.
没有一架飞机、没有一个飞行员已准备好起飞。
Here are two books. Either of them is worth reading.
这有两本书，都值得一读。
Neither of these two dictionaries contains this ward.
这两本词典都没收入这个字
Everyone is here. No one is absent. 大家都到了，没有人缺席。
Somebody is using the phone. 有人在用电话。
I have two sisters. One is here, and the other is not here.
我有两个姐妹，一个在这儿，一个不在这儿。
Each day is better than the one before. 一天比一天好。
Either day is OK. 两天中哪一天都行。
5. what，who，which，any，mare，some，half，mast，all，none.等代词可以是单数，也可以是复数，主要靠意思决定。但指不可数名词时作单数看待。
6.表示时间、重量、长度、价值等的单位名词，尽管是复数形式，如果作整体看待，动词都用单数形式。如果看作组成该数量的一个一个的个体，则动词用复数。
如：Twenty miles is a long way to walk. 走二十英里可是很长的一段路。
Ten years is a long time。十年很长。
Eight minutes is enough. 八分钟够了。
Twelve dollars is too dear. 十二美圆太贵了。
There are six silver dollars in each of the stacking. 每只袜子里有六个一美元的银币。
7. “the+形容词”表示一类人时，谓语动词用复数。表示抽象概念或指个别事物时谓语动词用单数。
如：The old are well taken care of. 老人得到很好的照顾。
The beautiful is laved by all. 人人都爱美。
8. 如果主语由"a kind/sort/type of this kind/sort/type of +名词”组成，不管名词是单数还是复数，动词通常用单数。
如：This kind of man annoys me. =This kind of men annoys me. 这种人让我烦。
This kind of apple is very expensive. = This kind of apples is…这种苹果很贵。
类似的还有:a portion of(一部分)，a series of(一系列)，a pile of(一堆)，a panel of (一个小组委员会)，
如：A series of accidents has happened here. 这里发生过一系列事故。
9. Means作“方法、手段”讲时，单复数同形，其前面有each, every, neither, either,等单数a念的定语时，谓语动词用单数;若有all, both，these等复数概念的定语时谓语动词用复数。
“None of the means”作主语时，谓语动词通常用单数。
如：There is/are no means of learning what is happening. 没法知道正在发生什么事。
No means is /are left untried. 没有没试过的方法了。
Every means is to an end. 每一种手段都能达到一种目的。
A bicycle is a means of transport. 自行车是一种交通手段。
All possible means have/Every possible means has been tried.所有的方法都试过了。
