1. Subjects and verbs must agree in number. This is the cornerstone rule that forms the background of the concept.
See:
The dog growls when he is angry.
The dogs growl when they are angry.
2. Don’t get confused by the words that come between the subject and verb; they do not affect agreement.
See:
The dog, who is chewing on my jeans, is usually very good.
3. Prepositional phrases between the subject and verb usually do not affect agreement.
Example:
The colors of the rainbow are beautiful.
4. When sentences start with “there” or “here,” the subject will always be placed after the verb, so care needs to be taken to identify it correctly.
Example:
There is a problem with the balance sheet. Here are the papers you requested.
5. Subjects don't always come before verbs in questions. Make sure you accurately identify the subject before deciding on the proper verb form to use.
Example:
Does Lefty usually eat grass? Where are the pieces of this puzzle?
6. If two subjects are joined by and, they typically require a plural verb form.
Example:
The cow and the pig are jumping over the moon.
7. The verb is singular if the two subjects separated by and refer to the same person or thing.
Example:
Curry and rice is my mom's favorite dish.
8. If one of the words each, every, or no comes before the subject, the verb is singular.
Example:
No smoking or drinking is allowed. Every man and woman is required to check in.
9. If the subjects are both singular and are connected by the words or, nor, neither/nor, either/or, and not only/but also the verb is singular.
Example:
Jessica or Christian is to blame for the accident.
10. Except for the pronouns (few, many, several, both, all, some) that always take the plural form.
Example:
Few were left alive after the flood.
11. If two infinitives are separated by and they take the plural form of the verb.
Example:
To walk and to chew gum require great skill.
12. When gerunds are used as the subject of a sentence, they take the singular verb form of the verb; but, when they are linked by and, they take the plural form.
Example:
Standing in the water was a bad idea.
Swimming in the ocean and playing drums are my hobbies.
13. Collective nouns like herd, senate, class, crowd, etc. usually take a singular verb form.
Example:
The herd is stampeding.
14. After one of, each of, either of, neither of Noun will be plural but Verb will be singular.
Example: Each of the students was given a prize.
15. Together with, along with, in addition to, with, including to, as well as, and not, accompanied by, accompanied with. When these phrases combine a subject, the verb will always be according to second subject.
Example: The guest, along with his wife and two daughters, is seated here.
16. A number of + plural noun + plural verb. The number of + plural noun singular verb
Example: A number of students are present here. The number of students is present here.
17. Titles of books, movies, novels, etc. are treated as singular and take a singular verb.
Example:
The Burbs is a movie starring Tom Hanks.
18. Remember, only the subject affects the verb!