Agreement within sentences is important. Agreement comes into play with pronouns and with verb tense. Prepositional phrases can also be a factor.

Pronouns are substitutes for nouns. The most commonly used are:
• Personal pronouns: I, you, we, he, she, it, me, us, him, her, they, them.
• Possessive pronouns: mine, yours, his, hers, its, ours, theirs.

A pronoun’s form — singular or plural — should agree with the number of people or objects to which it refers. These pronouns — anyone, anybody, everyone, everybody, someone, somebody, no one, nobody — always pair up with the singular form of the verb.

Nobody likes a tattle-tale.

Exceptions can be made. For example:

Everyone is invited to bring their children to work tomorrow.

“Everyone” is singular. “Their” is plural. According to old grammar rules, the correct pronoun to use is “his,” but this sounds strange if we’re referring to a mixed-gender group. “His or her” would also be grammatically correct, but it’s more awkward. The use of “their” in a case like this is so common that it’s increasingly considered acceptable. But it’s often easy to avoid the “singular/gender” dilemma by restructuring the sentence.

Original: Everyone is invited to bring their children to work tomorrow.
Restructured: You’re all invited to bring your children to work tomorrow.

Collective nouns refer to groups of people. In American English, they typically take a singular verb. The team needs more practice. The staff is leaving early for an off-site seminar. Congress is in recess for the summer.

Prepositions are words and phrases that indicate location in time or space. There are dozens, but the most commonly used are

above, about, across, against, along, among, around, at, before, behind, below, beneath, beside, between, beyond, by, down, during, except, for, from, in, inside, into, like, near, of, off, on, since, to, toward, through, under, until, up, upon, with, within

Prepositions usually appear in prepositional phrases: Around the corner, between the ears, since the move, within a week.

Prepositional phrases can cause problems with noun-verb agreement. The form of the verb — plural or singular — is dictated by the noun that is the subject of the sentence. A noun in a prepositional phrase is not the subject.

Wrong: This box of files belong in the storage room.
Right: This box of files belongs in the storage room.

Wrong: Each of these pots need to be scrubbed.
Right: Each of these pots needs to be scrubbed.

One of the most common cases of noun-verb agreement confusion involves the use of “I” and “me.” Generally, you use I when the pronoun comes before the verb, and me when it comes after.

Maria and I ordered pizza for lunch.
That pizza is for Maria and me.

The easiest way to determine which pronoun to use it to imagine the sentence without the other person in it. You wouldn’t say “That pizza is for I.”