Subject-Verb Agreement

The S-ending Rule for Prepositional Phrases

A prepositional phraseOpens in new window merely adds information to the subjectOpens in new window, but it does not change whether the nounOpens in new window is singular or plural.

Observe carefully the following examples:
  • (without a prep. phrase) The engineer is working hard.
  • (with a prep. phrase) The engineer at the controls is working hard.

In the first sentence, engineer is the subject, so is (a verb with an s–ending) is required. In the second sentence, engineer is still the subject, so is is still the correct verb. Controls is plural, but because it is not the subject, its s–ending doesn’t affect the verb.

But in the following examples, the reverse is the case:
  • (without a prep. phrase) The secretaries do a lot of typing.
  • (with a prep. phrase) The secretaries in the pool do a lot of typing.

In the first sentence, the verb do (without s–ending) is used because the subject secretaries is plural (with an s–ending). In the second sentence, the verb still remains do because the subject has remained secretaries. Pool is part of the prepositional phrase; it is not the subject and so has no effect on the verb.

The following represent another method:
  • (without a prep. phrase) These ledgers are inaccurate.
  • (with a prep. phrase) One of these ledgers is inaccurate.

In the first sentence, the verb are has no s–ending because the subject ledgers have an s–ending. But in the second sentence, the verb is, with an s–ending, is required because ledgers is no longer the subject; this time, one is the subject and ledgers is part of a prepositional phrase.