When you write a sentence you must make sure that the
subject and the verb agree.
If the subject is a singular noun, or the pronoun he, she
or it, you need a singular verb.
The zookeeper is feeding the animals.
The children are playing on the swings.
The earth moves round the sun.
Dad always drives to work.
The clerk is wrapping a package.
Does everyone know the answer?
Mom has bought a dress for Sara.
Use a plural verb if the subject is a plural noun, or the
pronoun we, you or they.
The two girls always walk home together.
The children are playing on the swing.
Collective nouns may be used with either singular or
plural verbs. If the group members are all acting together
as one, use a singular verb. If the members of the group
are acting as individuals, use a plural verb.
That family has moved to Texas.
The team is coached by Mr. Clark.
The family were giving their opinions.
The team are sharing new ideas.
Kaynak: Basic English Grammer Book1