主谓一致
1. many a, more than one +单数名词，谓语仍然用单数.
Many a soldier has sacrificed his life for the revolution.
2. either of +复数名词，谓语动词用单数.
Has either of your parents visited you?
3. and; both and 连接两个单数形式的名词词组，谓语动词用复数.当主语在意义上指同一人，同一物或同一概念时，谓语用单数.
A boy and a girl want to go.
A cart and horse is what he needs now.
在英语中，有不少像a cart and horse这种表示单数概念的短语，如：
a needle and thread a knife and fork
a watch and chain a cup and saucer
即使这种表示单数概念的短语中有复数名词，谓语动词仍然用单数形式，如：
Danish bacon and eggs makes a good solid English breakfast.
More examples: bread and butter, trial and error, law and order, toast and marmalade, fish and chips
4. each and each; every and every 等结构后，谓语用单数.
Each man and (each) woman is asked to help.
5.主语后面有as well as; together with; along with; rather than等词组，谓语的单复数有主语来决定.
6. one of+复数名词+关系分句结构，如先行词为复数名词，谓语则为复数.当前面有the only/very等限定词修饰，谓语用单数.
Joan is one of those people who go out of their way to be helpful.
He is the only one of those boys who is willing to take on another assignment.
7.靠近原则：
由 not only...but also, either...or, neither...nor 或 or 连接的并列主语，通常根据 就近一致 原则，谓语动词的单复数形式由最接近它的名词词组的单复数形式决定。例如：
He or you have taken my pen.
Neither the students nor the teacher knows anything about it .
One or two days are enough to visit the city.
8. 由 “a number of, a total of + 复数名词 ” 作主语，谓语动词用复数形式;由 “the number of, the total of+ 复数名词 ” ，谓语动词用单数形式。例如：
A number of students are waiting for the bus.
The number of the students in this university is increasing yearly.