In a compound subject, two or more subjects join together to share the verb in a sentence.
Two issues to watch out for with compound subjects are pronoun usage and verb agreement. Use a subject pronoun (e.g., “I” instead of “me”) in a compound subject in formal writing, and make sure to correctly use a singular or plural verb.
A compound subject is made up of two or more subjects joined together to share the same verb in a sentence. Words like and are used to connect multiple phrases to form a compound subject.
When two or more subjects join together to form a compound subject, they share the predicate .
Two noun phrases (Rita + her friends) form a compound subject to then share the rest of the sentence, or the predicate.
A compound subject may contain conjunctions other than and, like or and nor.
A compound subject may comprise only singular nouns, only plural nouns, or a mix of singular and plural.
Your main concern with compound subjects is agreement —that is, use of correct pronouns and verbs in a sentence.
The use of pronouns in a compound subject is governed by grammar rules as well as considerations of formality and politeness. In general, in formal writing , use subject pronouns in a compound subject: I, he, she, and they, rather than me, him, her, and them.
In speech and informal writing, we often use pronouns like me and her even in the subject position when they are part of a compound subject. While this is acceptable informally, avoid such usage in formal texts.
Sometimes, reflexive pronouns like myself and yourself, not generally used in the subject position, are used for the sake of politeness. Such usage is rare but not incorrect, especially in speech.
Compound subjects joined by and are usually considered plural and take plural verbs (e.g., are instead of is).
Sometimes, two nouns joined by and are thought of as one idea rather than two. Although such a subject contains and, it is treated as singular.
Two or more singular nouns joined by or, nor, and as well as take singular verbs.
When one of the nouns is singular and the other plural, the verb generally agrees with the noun closest to it.
In formal writing, be careful to use the correct pronoun in a compound subject. Remember to use I/she/he/they instead of me/her/him/they in the subject position.
Also remember that a compound subject containing and is usually plural. In contrast, singular noun phrases joined by or, nor, or as well as are considered singular and take singular verbs.
Also watch out for excessively long compound subjects made up of multiple noun phrases. It’s easy to mistakenly use the wrong verb form with such subjects.
Since the noun adjacent to the verb is “vaccine,” the writer may be fooled into using a singular verb. In fact, the compound subject has two noun phrases joined by and. It is therefore plural.
Moreover, if the subject is overly long, readers may find it hard to follow along. By the time they reach the end of the sentence, they may have forgotten what it is you were talking about.
