Subjects must agree with verbs and pronouns must agree with antecedents. The basic rule of sentence agreement is really quite simple: A subject must agree with its verb in number. (The number can be singular or plural.) Here's how it works.
Singular Subjects and Verbs
In grammar, number refers to the two forms of a word: singular (one) or plural (more than one). A singular subject takes a singular verb.
The boy sings.
The singular subject the boy agrees with the singular verb sings.
He likes coffee.
The singular subject he agrees with the singular verb likes.
He is the oldest man to climb Mt Everest.
The singular subject he agrees with the singular verb is.
Plural subjects that function as a single unit take a singular verb.
Age and experience brings wisdom.
Slow and steady wins the race.
Bread and butter is what they want.
Ham and eggs was the breakfast of champions in the 1950s.
Titles are always singular. It doesn't matter how long the title is, what it names, or whether or not it sounds plural. As a result, a title always takes a singular verb.
The Crusades is a book that comes in two volumes.
The singular title The Crusades agrees with the singular verb is - even though the title appears plural, it is singular. That's because all titles are singular.
Bombay Times is my favourite newspaper.
The singular title Bombay Times agrees with the singular verb is.
The Valachi Papers is a good read.
The singular title The Valachi Papers agrees with the singular verb is - even though the title appears plural, it is singular.
Other examples are given below.
Memories of the War is worth reading.
Moby Dick is the tale of a whale.
Singular subjects connected by or, either/or, neither/nor, and not only/but also require a singular verb.
Neither John nor Peter has any right to the property.
Either the witness or the defendant was lying.
No prize or medal was given to the boy, though he stood first in the examination.
An apple or a pear contains about 75 calories each.