Elementary Rule 9. The number of the subject determines the number of the verb.
有时候区分主语到底是单数还是复数并不简单。试看下面一句话是否表达正确：
The bittersweet flavor of youth — its trials, its joys, its adventures, its challenges — are not soon forgotten.
1. Words that intervene between subject and verb do not affect the number of the verb.（主语和动词之间的词语不改变主语的单复数）
所以上面一句话的动词应该用单数：
The bittersweet flavor of youth — its trials, its joys, its adventures, its challenges — is not soon forgotten.
2. A common blunder is the use of a singular verb form in a relative clause following "one of..." or a similar expression when the relative is the subject.（一个常见的错误是在类似"one of..." 之后使用动词的单数形式）
One of the ablest scientists who has attacked this problem.
3. Use a singular verb form after each, either, everyone, everybody, neither, nobody, someone.
.Everybody thinks he has a unique sense of humor.
4. With none, use the singular verb when the word means "no one" or "not one."; （当none表示没有一个的时候，跟单数动词）
None of us is perfect.
A plural verb is commonly used when none suggests more than one thing or person.（当none表示多个的时候，跟复数动词）
None are so fallible as those who are sure they're right.
5. A compound subject formed of two or more nouns joined by and almost always requires a plural verb.（复合名词后通常跟复数动词）
The walrus and the carpenter were walking close at hand.
6. But certain compounds, often cliches, are so inseparable they are considered a unit and so take a singular verb, as do compound subjects qualified by each or every. （不过，有些特定的复合名词，则需要用单数动词）
The long and the short of it is ...
Bread and butter was all she served.
Give and take is essential to a happy household.
Every window, picture, and mirror was smashed.
7. A singular subject remains singular even if other nouns are connected to it by with, as well as, in addition to, except, together with , and no less than.（当有其它的名词以with, as well as, in addition to, except, together with , and no less than的形式连缀主语之后，依然用单数动词）
His speech as well as his manner is objectionable.
8. A linking verb agrees with the number of its subject. （动词的单复数与主语一直，与宾语无关）
What is wanted is a few more pairs of hands.
The trouble with truth is its many varieties
9. Some nouns that appear to be plural are usually construed as singular and given a singular verb.（有些看似是复数的名词却应该使用单数动词）
Politics is an art, not a science.
The Republican Headquarters is on this side of the tracks.
不过：
The general's quarters are across the river.
从上述的例子当中可以看出，有时候我们需要不断了解一些俗语性的表达习惯，才能够准确地判断到底应该用单数还是复数的动词格式，否则我们很容易就会错用动词的单复数形式。
