Grammar
Subject-Verb Agreement
The subject and verb in a sentence must agree, or work together. A singular subject needs a singular verb. A plural subject needs a plural verb.
Use the following rules for verbs that tell about the present time.
If the subject is a singular noun or he, she, or it, add -s or -es to most verbs.
A horse runs. A dog chases the horse. It barks loudly.
If the subject is a plural noun or I, you, we, or they, do not add -s or -es to the verb.
Horses run. Dogs chase the horses. They bark loudly.
For the verb be, use am and is to agree with singular subjects and are to agree with plural subjects.
I am afraid. Paul is fearless. The armies are here.