Subject- verb concord

Concord (another word for agreement) is a grammatical relationship of the words, which affects the form of one or more of them.

In English we can distinguish three types of concord:

grammatical ? following a form of the words
notional ? based rather on the meaning than on the form of the words
proximity concord

General rules:

We use singular form of the verb when:
the subject has a singular form and a singular meaning:
He sees that it is better to live in peace.
He was certainly a happy fellow at this time.

when the subject is a collective noun which represents a number of persons or things taken as one unit; such as:
The larger breed (of camels) is capable of transporting a weight of a thousand pounds.
Another school professes entirely opposite principles.

when the subject consists of two or more singular nouns connected by or or nor; as
Jesus is not dead, nor John, nor Paul, nor Mahomet.
It is by no means sure that either our literature, or the great intellectual life of our nation, has got already, without academies, all that academies can give.

When the subject is plural in form, but represents a number of things to be taken together as forming one unit; for example:
Between ourselves, three pounds five shillings and two pence is no bad day's work.
Two thirds of this is mine by right.

The singular form is also used with book titles, other names, and other singulars of plural form; as:
Politics is the only field now open for me.

With several singular subjects not disjoined by or or nor, in the following cases:
Joined by ?and?, but considered as meaning about the same thing, or as making up one general idea; such as:
In a word, all his conversation and knowledge has been in the female world.
The genius and merit of a rising poet was celebrated.
Not joined by a conjunction, but each one emphatic, or considered as appositional; for example:
The author, the wit, the partisan, the fine gentleman, does not take the place of the man.
To receive presents or a bribe, to be guilty of collusion in any way with a suitor, was punished, in a judge, with death.

This use of several subjects with a singular verb is especially frequent when the subjects are after the verb; as:
There is a right and a wrong in them.
Then comes the "Why, sir!" and the "What then, sir?" and the "No, sir!"
Joined by ?as well as? (in this case the verb agrees with the first of the two, no matter if the second is plural); thus:
Asia, as well as Europe, was dazzled.
The Epic, as well as the Drama, is divided into tragedy and Comedy.
When each of two or more singular subjects is preceded by ?every, each, no, many a?, and such like adjectives:
Every fop, every boor, every valet, is a man of wit.
Every sound, every echo, was listened to for five hours.

The plural form of the verb is used:
When the subject is plural in form and in meaning:
These bits of wood were covered on every square.
The Arabian poets were the historians and moralists.

When the subject is a collective noun in which the individuals of the collection are thought of; as:
A great number of people were collected at a vendue.
A party of workmen were removing the horses.

When the subject consists of several singulars connected by ?and?, making up a plural subject, for example:
Only Vice and Misery are abroad.
His clothes, shirt, and skin were all of the same color

The conjunction may be omitted, , but the verb is plural, as with a subject of plural form.
A shady grove, a green pasture, a stream of fresh water, are sufficient to attract a colony.

When a singular is joined with a plural by a disjunctive word, the verb agrees with the one nearest it; as:
One or two of the ladies were going to leave.

If there is only one person in the subject, the ending of the verb indicates the person of its subject; that is, in those few cases where there are forms for different persons: as:
Romanism wisely provides for the childish in men.

If the subject is made up of the first person joined with the second or third by and, the verb takes the construction of the first person, the subject being really equivalent to we; as:
I flatter myself you and I shall meet again.
You and I are tolerably modest people.

When the subjects, of different persons, are connected by adversative or disjunctive conjunctions, the verb usually agrees with the pronoun nearest to it; for example:
Neither you nor I should be a bit the better or wiser.
Not Altamont, but you have been my lord.

Sources:

1.Kenneth G. Wilson: Notional agreement (Notional Concord) (from http://www.bartleby.com/68/28/4128.html).
2.Jamal Ardehali: Subject Complement?Verb Concord in English (from http://www.arts.gla.ac.uk/SESLL/STELLA/COMET/glasgrev/issue4/jamal.htm).
3.Concord ? definition from http://www.usingenglish.com/glossary/concord.html.
4.Concord of verb and subject in manner (from http://www.lousywriter.com/syntax_verbs.php)