Subject/Verb Agreement

 

The general rule for subject-verb agreement is that in any sentence, the verb or the auxiliary must agree with the subject in person and number. Yet before making decisions about person and number, we must make sure that we have the right subject. This may be difficult when subject and verb are separated by prepositional phrases (phrases introduced by prepositions), direct objects, or dependent clauses (clauses that cannot stand by themselves as sentences and are introduced by pronouns, adverbs, etc.).

A prepositional phrase following the subject does not determine the number of the verb

One of the boys is wearing a red shirt.

We must be careful not to confuse a direct object with the subject of the sentence. 

Combating spam, malware, and attacks on the network has been a concern of the Internet community for years.
 
Nouns that are part of a dependent clause cannot be the subject of the sentence.

The artist who paints street musicians, vendors, and beggars captures the real vibe of a city.