Collective nouns are usually treated as singular and take singular verbs. However, they may take a plural verb when we are talking about the individual members within the group.
- An unruly mob was gathering outside.
- The mob were (i.e., members) scattered in all directions.
A number of
The phrase a number of should be followed by a plural noun and a plural verb.
- A number of objections were raised against the proposal.
- A number of issues still need to be resolved.
When the sentence begins with ‘The number of’, the verb should be singular.
- The number of available jobs is shrinking rapidly. (Here the subject is ‘number’, not ‘jobs’.)
A half of, a part of
Fractional expressions such as a half of, a part of and a majority of can be followed by a singular or a plural verb. It depends on the meaning.
- A large percentage of the population is angry with the ruling party.
- Nearly 60 percent of the members are in favor of the new policy.
The expression ‘more than one’ takes a singular verb.
- More than one student has tried to cheat on the exam.
- More than one person has been diagnosed with swine flu.
A positive and a negative subject together
When you put a positive and a negative subject together, the verb must agree with the positive subject.
- The members, but not the chairman, have decided to vote against the proposal. (Here the plural verb have agrees with the positive subject ‘the members’.)
- It is his attitude, not his ideas, that invites criticism.
A plural noun that names a single subject
When a group of words containing a plural noun represents a single object, you must use a singular verb.
- The Adventures of Tom Sawyer was enjoyed by us all.
- Gulliver’s Travels was written by Jonathan Swift.
- Thrice-told Tales is an interesting book.
None should be used with a singular verb. A plural verb is also possible in a less careful style.
- None of his friends was there to help him. (Formal)
- None of his friends were there to help him. (Less formal)