COMMON ERROR 6: DISAGREEMENT OF SUBJECT AND VERB

A verb must agree in number with its subject. Make sure that an intervening phrase doesn’t mislead you.

WRONG The pile of forms are on the desk.
RIGHT The pile of forms is on the desk.

WRONG A considerable proportion of the bills are unpaid.
RIGHT A considerable proportion of the bills is unpaid.

Watch also when a phrase follows the subject, separated by commas or brackets:

The child, as well as her mother, looks tired.
The lawyer, with his two clients, is waiting at the court.
Lousy driving is to result in lousy road accidents.

When the subject has 2 parts separated by or the verb will be singular or plural, depending on the number of the parts:

Either Ali or his brother has made this mess.
but
Neither the men nor the womenare responsible.

When 1 part is singular and the other plural, the verb agrees with the closer:

Neither the professor nor the students have stayed in the smoke-filled room.
and
Neither the students nor the professor has stayed in the smoke-filled room.

If you don’t like the sound of the last 2, change your sentence in some way e.g.
The students have not stayed in the smoke-filled room, nor has the professor.

A different but related error occurs when the subject agrees with only part of the verb. You need a past participle (refer blog entry: December 29, 2005; PARTS OF SPEECH: PARTICLE & PARTICIPLE) after a helping or auxiliary verb e.g. ‘is’ or ‘has’.

WRONG Documents are design by graphic artists.
RIGHT Documents are designed by graphic artists.

WRONG The campaign was complete by the deadline.
RIGHT The campaign was completed by the deadline.