In the present tense, if the subject is a HE, SHE, or IT (singular subjects), the verb has an -S on it:
HE WALKS, SHE WALKS, IT WALKS.
Any other subject (plural subjects) will not have an -S on the verb:
I WALK, WE WALK, YOU WALK, THEY WALK.
1. Make sure you find the correct subject.
a. The subject is not in a prepositional phrase:
One of the apples tastes sour. (ONE TASTES)
b. In a participial or infinitive phrase, don't mistake the object of the participle or infinitive
for the subject:
Running long races requires stamina. (RUNNING REQUIRES)
c. Don't mistake words in a subordinate clause for the subject in a main clause:
The man who wrote the letters wants to see you. (MAN WANTS)
2. Make sure you know some special subject-verb agreement rules.
a. Collective nouns are singular: The committee meets here. (COMMITTEE MEETS)
b. When subjects are separated by OR or NOR, the verb agrees with the subject that is
closest to it: Either the teacher or the students need help. (STUDENTS NEED)
c. When WHO, WHICH, or THAT is used as a subject, find the word that the pronoun
stands for. If that word is singular, the pronoun is singular; if it is plural, the pronoun
The squirrels that live in our backyard are amusing. (SQUIRRELS=THAT LIVE)
d. When AND joins two subjects, the subject is plural:
Ethel and Frank like pizza. (ETHEL & FRANK LIKE)
e. When participles and infinitives are used as subjects, they are singular:
Running provides excellent exercise. (RUNNING PROVIDES)
f. Remember that indefinite pronouns (EACH, EVERYONE, EVERYBODY, ONE,
ETC.) are singular: Everybody likes Sam. (EVERYBODY LIKES)
g. The words THERE and HERE are never subjects. When a sentence starts with these
words, the subject usually comes after the verb:
There comes the boss. (BOSS COMES)
3. Be aware of the singular and plural forms of irregular verbs (TO BE, TO DO, TO HAVE).
TO BE: I am, you are, he is, she is, it is
we are, you are, they are
I was, you were, he was, she was, it was
we were, you were, they were
TO DO: I do, you do, he does, she does, it does
we do, you do, they do
TO HAVE: I have, you have, he has, she has, it has
we have, you have, they have