Subject and Verb Agreement

Definition

=> The part of a sentence or clause that commonly indicates (a) what it is about, or (b) who or what performs the action (that is, the agent).

=> The subject is typically a noun, noun phrase, or pronoun. In a declarative sentence, the subject usually appears before the verb ("Gus never smiles"). In an interrogative sentence, the subject usually follows the first part of a verb ("Does Gus ever smile?").

As discussed below, there are exceptions to this traditional definition of a subject.

How to Identify the Subject:

"The clearest way of spotting the subject of a sentence is to turn the sentence into a yes-no question (by this we mean a question which can be answered with either 'yes' or 'no'). In English, questions are formed by reversing the order between the subject and the first verb which follows it. Look at the following example:

He can keep a Tamagotchi alive for more than a week.

The appropriate question here if we want a 'yes' or 'no' as an answer is:

Can he keep a Tamagotchi alive for more than a week?

Here 'he' and 'can' have changed places and that means that 'he' must be the subject in the first sentence. . . .

"If there is no suitable verb in the original sentence, then use dummy do, and the subject is the constituent which occurs between do and the original verb."

Examples and Observations:

• "My master made me this collar. He is a good and smart master, and he made me this collar so that I may speak."
• "Baseball is dull only to dull minds."

Subject-Verb Agreement

 

In the present tense, a verb must agree in number with its subject. That, of course, is the basic principle of subject-verb agreement. It's a simple enough rule, but on certain occasions even experienced writers can slip up on it.

Let's have a look at three of the trickier cases of subject-verb agreement:

1. making subject and verb agree when words come between them;
2. reaching agreement when the subject is an indefinite pronoun; and
3. making the verbs have, do, and be agree with their subjects.

CASE #1: Making Subject and Verb Agree When Words Come Between Them

In determining subject-verb agreement, don't let yourself be confused by words that come between the subject and the verb. Let's compare these two sentences:

This box belongs in the attic.
This box of ornaments belongs in the attic.

In both sentences, the verb belongs agrees with its subject, box. Don't let the prepositional phrase in the second sentence fool you into thinking that ornaments is the subject. It is simply the object of the preposition of and does not affect the agreement of subject and verb.

Prepositional phrases (as well as adjective clauses, appositives, and participle phrases) often come between a subject and a verb. So to make sure that a verb agrees with its subject and not with a word in the phrase or clause, mentally cross out the interrupting group of words:

One (of my sister's friends) is a pilot.
The people (who survived the explosion) are in a shelter.
A man (chasing unicorns) is on the terrace.

Remember, then, that the subject is not always the noun closest to the verb. It is the noun (or pronoun) that names what the sentence is about, and it may be separated by several words from the verb.

CASE #2: Reaching Agreement When the Subject Is an Indefinite Pronoun

Remember to add an -s to the end of the verb in the present tense if the subject is one of the indefinite pronouns listed below:

• one (anyone, everyone, no one, someone)
  
• anybody (everybody, somebody, nobody)
  
• anything (everything, something, nothing)
  
• each, either, neither

As a general rule, treat these words as third-person singular pronouns (he, she, it).

In the following sentences, each subject is an indefinite pronoun and each verb ends in -s:

Nobody claims to be perfect.
Everybody plays the fool sometimes.
Each of the divers has an oxygen tank.

In that last sentence, note that has agrees with the subject each, not with divers (the object of the preposition).

CASE #3: Making Have, Do, and Be Agree with Their Subjects

Although all verbs follow the same principle of agreement, certain verbs seem to be a little more troublesome than others. In particular, many agreement errors result from the misuse of the common verbs have, do, and be.

We need to remember that the verb have appears as has if the subject is a singular noun or a third-person singular pronoun (he, she, it):

Dana Barrett has ghosts in her bedroom.

If the subject is a plural noun or the pronoun I, you, we, or they, use have:

The Ghostbusters have a new client.

In a nutshell, "She has," but "They have."

Similarly, the verb do appears as does if the subject is a singular noun or, once again, a third-person singular pronoun (he, she, it):

Gus does the housework.

If the subject is a plural noun or the pronoun I, you, we, or they, use do:

Gus and Merdine do the chores together.

Are you beginning to see a pattern here? Then let's mix it up just a little bit.

The verb be has three forms in the present tense: is, am, are. Use is if the subject is a singular noun or a third-person singular pronoun (he, she, it):

Dr. Venkman is unhappy.

Use am if the subject is the first-person singular pronoun (I):

I am not the person you think I am.

Finally, if the subject is a plural noun or the pronoun you, we, or they, use are:

The fans are in the stands, and we are ready to play.

Now, let's take one more look at these three verbs--but from a different angle.

Sometimes a subject may follow (rather than precede) a form of the verb have, do, and be. As shown in the sentences below, this reversal of the usual order occurs in questions that require a helping verb:

Where has Egon parked the car?

What do you do in your free time?

Are we having a test today?

In all of these sentences, the present forms of have, do, and be serve as <"helping verbs" and appear in front of their subjects. Another case in which a form of the verb be comes before the subject is in sentences beginning with the words there or here:

There is a unicorn in the garden.

Here are the photocopies.

Just keep in mind that no matter where a verb appears in a sentence, it must still agree with its subject.

source : http://grammar.about.com/od/rs/g/subject.htm
             http://grammar.about.com/od/correctingerrors/a/SpecSVA.htm