- A sentence has a compound subject when it has more than one subject. It has a compound predicate when there is more than one predicate. Sometimes sentences can have both a compound subject and a compound predicate.
Rachel and Steffi read the same book. (compound subject)
Ulysses ran, swam, and rode a bicycle in the triathlon. (compound predicate)
My dog and ferrets play and sleep together. (compound subject and predicate)
Compound subjects and predicates are joined with either the coordinating conjunctions (and, but, or, nor) or the correlative conjunctions (both/and, either/or, neither/nor, not only/but also).
- Don't confuse a verb phrase with a compound predicate.
We will be going to China this summer. (verb phrase - it has only one main verb - going)
A compound predicate might share a helping verb, or it might be two (or more) separate verb phrases.
Dolphins are swimming and splashing near our dock. (swimming and splashing share the helping verb are.)
Dolphins do swim and do splash near our dock. (do swim and do splash have the same helping verb but are two separate verb phrases.)
Dolphins do swim and might splash near our dock (do swim and might splash are two separate verb phrases.).
- Don't confuse a simple sentence with a compound subject and predicate with a compound sentence.
Sam and Clarence are talking and eating at the same time. (compound subject and predicate - notice the pattern: subject, subject, verb, verb. Both subjects are doing both verbs.)
Sam is talking, and Clarence is eating at the same time. (compound sentence - notice the pattern: subject, verb, subject, verb. The first subject is doing the first verb, and the second subject is doing the second verb.)