Subject-Verb Agreement
Every sentence has a subject and a verb. The subject-verb agreement means that the verb must agree with the subject of the sentence. It means that a correct verb should be used according to the singular or plural nature of the subject.
For instacne, different helping verbs (e.g., is, are, was, were, has, have) are used for singular or plural subject. The use of these verbs varies according to the singular or plural nature of a subject as well as the way the subjects have been presented in a sentence.
The basic rule for subject-verb agreement is: a singular verb is used for a singular subject whereas a plural verb is used for a plural subject in a sentence.
However, there are some rules of English grammar which apply to subject-verb agreement when the singular or plural nature of the subect may change due to the way they are presented. Lets read a simple example here before learning the rules.
Example.
- David has moved to a new house.
- David and Sara have moved to a new house.
- David, along with his wife, has moved to a new home.
- In the first sentence, the singular helping verb ‘has’ is used because the subject ‘David’ is singular (e.g., one person).
- In the second sentence, the plural helping verb ‘have’ is used because the subjects (David and Sara) are plural (two persons).
- In the third sentence, there are still two persons but the singular helping verb ‘has’ is used. This is because when the words ‘along with’ joins two or more subjects together, the helping verb is used according to the first subject (e.g., David).
The rules of subject-verb agreement are as follows:

Examples.
- John and David are going to a zoo.
- He and his friend have finished the work.
- David and Sara were decorating the room.
- I and he are going to school.
- John, David, and Sara have passed the exam.
- She and her children are eating a pizza.
- He and his friends were enjoying the party.
It can be seen in the above examples, that whether the nouns or pronouns joined by ‘and’ are singular or plural, a plural verb is used.

Examples.
- Neither David nor Sara is interested in music.
- Either he or his brother has broken this cup.
- Neither he nor his brother has paid the bill.
- David, John, or Sara has to answer this question.

Examples.
- Neither he nor his friends are attending the lectures.
- Neither his friends nor he is attending the lectures.
- Either she or her kids are talking to someone on phone.
- Either her kids or she is talking to someone on phone.
- Neither she nor her friends have finished the work.
- Neither her friends nor she has finished the work.

Examples.
- The list of guidelines were prepared. (Wrong).
- The list of guidelines was prepared. (Correct).
- A group of students are trained for the game. (Wrong).
- A group of students is trained for the game. (Correct).

Examples.
- John, accompanied by his friends, is going to a cinema.
- He, along with other students, has participated in the competition.
- She, as well as her brother, has applied for a visa.
- Three patients along with a doctor were present in the room.
- The kids along with a woman are walking in the garden.

Examples.
- Our team is playing well.
- The committee has prepared a report.
- His family was concerned about his studies.
- Water is flowing in the river.

Examples.
- There are many people in the market.
- There is a crowd of people in the market.
- Here are some instructions for the exam.
- Here is a list of instructions for the exam.

Examples.
- None of them was ready to take the risk.
- Everyone in the hall was laughing.
- Each of these fruits is delicious.
- Someone is knocking at the door.
- Neither of the proposed plans has worked well.