1、语法上的一致
所谓语法一致原则，即主语和谓语的语法形式在人称和数上取得一致。
谓语的单、复数形式依据主语的单、复数形式而定：主语为复数，谓语动词用复数；主语为单数或者是不可数名词，谓语动词用单数。
China belongs to the Third World. 中国属于第三世界。
We are sure he will come. 我们肯定他会来。
使用语法一致的情况
（1）当主语是and，both…and连接的并列结构
如果主语指的是两个或两个以上的人或物，则谓语动词用复数。
My mother and I have seen the film. 我妈妈和我已看过这部电影。
Both rice and wheat are grown in this part of China. 在中国的这个地方既种稻子又种小麦。
注意：由and连接的并列主语前面分别有each，every，no修饰时，其谓语动词用单数形式。
Every boy and every girl has to receive education in our country. 在我国每一个男女孩子都得受教育。
No student and no teacher was invited to the party. 师生没有被邀请参加晚会。
（2）主语后面接说明主语的修饰语
主语后面接说明主语的修饰语如：
with，along with，together with，as well as，like，rather than，but，except，besides，including，in addition to，
谓语动词不受修饰成分的影响，仍保持同主语一致的关系。
The teacher with two students was at the meeting. 那位老师和两个学生参加了会议。
The girl as well as the boys has learned to drive a car. 这个姑娘和男孩子一道，也学会了开汽车。
A library with five thousand books is offered to the nation as a gift.一个有5000册书的图书馆作为礼物赠送给了国家。
E-mail, as well as telephones, is playing an important part in daily communication.电邮和电话在日常的通信中起着很重要的作用。
Nobody but Jane knows the secret.只有简知道这个秘密。
All but one were here just now. 刚才除了一个人外都来了。
（3）非谓语动词或从句作主语
非谓语动词 (动词的-ing形式、不定式)或从句作主语时，谓语一般用单数形式。
When and where to build the new factory is not decided yet.什么时候在什么地方建新工厂还没定下来。
Checking information is very important. 核实事实是非常重要的。
To learn foreign languages is not easy. 学习外语并非易事。
When we will hold the meeting is not decided yet. 我们何时开会尚未决定。
注意：当what引导主语从句或由 and连接两个动词不定式或动名词作主语时，谓语动词的数应根据意义一致的原则来决定。
What we need here is money．我们这里需要的是资金。
What we need here are workers．我们这里需要的是工人。
Lying and stealing are immoral．说谎与偷窃是不道德的。
（4）each和复合不定代词作主语
each和some/any/no//every十body/one/thing构成的复合不定代词：
anyone、anybody、anything、everyone、everybody、everything、someone、somebody、something、no one、nobody、nothing、each、the other作主语，谓语动词用单数。
Each is worse than the one before. 一个比一个差。
Nobody knows the answer. 没有一个人知道这答案。
Someone wants to see you. 有人想见你。
Is there anything in the box?箱子里有什么东西吗?
There is a lot of milk in the bottle. 瓶子里有很多奶。
（5）“many a +单数名词”作主语
“many a、(很多)/more than one(不只一个)+单数名词”作主语时，谓语动词用单数形式。
Many a student has been to Beijing. 很多学生去过北京。
There is more than one answer to your question. 你的问题不只有一个答案。
（6）“one of+复数名词十定语从句”之前有the等限定词和修饰语
“one of+复数名词十定语从句”之前有the only，the very，the等限定词和修饰语时，定语从句的谓语动词用单数形式。
Tom is the only one of those boys who is willing to help the old man.
汤姆是唯一的一个愿意帮助那个老人的男孩。
He is the only one of the students who has been a winner of scholarship for three years．他是这三年来唯一的一个获得奖学金的学生。
注意:如没有这些限定词和修饰语，定语从句的谓语动词采用复数形式。
Tom is one of the boys who are always ready to help others. 汤姆是个随时愿意帮助别人的男孩。
（7）由两个部分组成的物体名词作主语
英语中有些由两个部分组成的物体名称如g1asses(眼镜)，scissors(剪刀)，shorts(短裤)，shoes(鞋子)，trousers(裤子)等作主语，其后的谓语动词用复数形式。
His glasses were broken, so he can't see well. 他的眼镜碎了，因而看不清楚。
His trousers are made of cotton. 他的裤子是棉布的。
注意:若这类名词前带有pair等表示单位的名词时，则以这些名词的单、复数形式决定动词的形式。
Two pairs of trousers are missing. 两条裤子不见了。
This pair of shoes is not on sale. 这双鞋不出售。

2、意义上的一致
意义上的一致是指谓语动词与主语的一致取决于主语所表达的意义。若主语形式上为复数，而意义上是单数，动词要用单数；
若主语形式上为单数，而意义上为复数，则动词用复数。
The United States is in North America. 美国在北美洲。
The police are looking into the matter. 警察正在调查此事。
使意义上的一致的情况
（1）由and连接两个并列主语
其后的谓语动词一般用复数形式。但如果两个单数名词指同一个人、同一事物、单一概念时，谓语动词要用单数，有时两个名词共用一个冠词。
The worker and writer has written a new novel. 这位工人兼作家写了一部新小说。(两个名词共用一个冠词)
There is a journalist and writer living in America whose name is Alex Haley. 在美国有一个名叫亚利克斯?哈利的记者兼作家。
Truth and honesty is always the best policy. 真诚总是上策。
注意：用and连接起来的两个单数主语，谓语动词可以是单数，也可以是复数。
Three and five makes /make eight.三加五等于八。
Time and tide wait/waits for no man .岁月不等人。
（2）形复意单的名词作主语
①复数形式的专有名词（表示国家、城市、机构、组织以及书籍、报纸、杂志等）做主语，通常作为整体看待，谓语动词用单数。
The United States is in North America.美国在北美洲。
The Arabian Nights is read all over the world.《天方夜谭》是流传世界各地的名著。
The New York Times has a wide circulation.《纽约时报》销路很广。
注意：表示山脉、群岛、瀑布等的专有名词和以复数形式出现的表示同姓的一家人或同名、同姓的若干人，谓语也用复数。
The Alps rise over 4 countries.阿尔卑斯山脉跨越了四国。
Niagara Falls are not as high as Victoria Falls.尼亚加拉瀑布没有维多利亚瀑布高。
The Smiths were also invited.史密斯一家人也受到了邀请。
There are 3 Marys and 2 Roberts in my class.我班有三个叫玛丽、两个叫罗伯特的学生。
②以-ics结尾表示学科的名词做主语，通常表示单数意义，谓语动词用单数形式。这类名词有：
physics, politics, mathematics, economics, athletics, electronics等。
Politics is now taught in all schools.现在各学校都开设政治课。
Economics is a science of the way in which industry and trade produce and use wealth.经济学是研究工业、贸易生财和用财之道。
注意：当这些动词表示有关方面的活动、情况、见解、原理等意思时，谓语动词需用复数形式。
What are his politics?他的政见如何？
The economics of national growth are of the greatest importance to all modern governments.国家发展经济的原理对现代各国政府都重要。
③news，maths，plastics，physics，works，means(方法)，the United States等虽然以-s结尾，但意义上作为单数看待。
“News of victories keeps pouring in as our army advances,” the company commander said. 集团军司令说：”
随着我们军队的推进胜利的消息接踵而至。”
Mathematics/Physics is a required subject for us.
数学/物理是我们必修的科目。
Every possible means has been used to prevent the air pollution，but the sky is still not clear.
所有可能的直至污染的方法都用了，但天空还是不晴朗的。
④成对的名词做主语时用单数形式。
Bread and butter is a daily food in the West .面包抹黄油是西方人每天的食品。
His gratitude and devotion to the Party is endless.他无限感觉，无限忠于党。
⑤“one and a half +复数名词”做主语，谓语动词用单数。
One and a half pears is left on the table .一只半梨剩在桌子上。
One and a half days is all I can spare.一天半是我所能挤出的全部时间。
注意：“one or two+复数名词”做主语，谓语动词用复数。
One or two days are enough to see the city.参观该市一两天就足够了。
There are one or two things I want to talk over with you .我有一两件事想跟你商量。
（3）有生命的集体名词作主语
有生命的集体名词 (如people，police，cattle，militia)作主语，谓语动词用复数形式。
Cattle are also kept. 还养了一些牛。
There are many people there. 那里有很多人。
The police are looking for the thief. 公安人员在搜寻那个小偷。
All the people of the world want peace.全世界人民都渴望和平。