The singular and plural forms of certain present-tense verbs are irregular. The pronoun (subject of the verb) must agree with the verb (subject).
I am one of the best grammarians in the class.
He is the fastest swimmer on the team.
It is a beautiful day for gardening.
We were entertained by the clowns.
You have the right idea.
They do want to take a walk before dinner.
The horse is whinnying.
Red is a good color for that curtain.
The little girl was happy.
The salad has enough lettuce.
Those do not match these.
The horses are running.
The lights are glowing
Those are delicious chocolates.
He and she were friends for a long time.
They have a lot to do today.
Exercise 1: Noun-Verb Agreement