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 Steffiread the same book. (compound subject) Ulyssesran, swam, and rode a bicycle in the triathlon. (compound predicate)
My dog and ferretsplay 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.
Wewill 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.
Dolphinsare swimming and splashing near our dock. (swimming and splashing share the helping verb are.) Dolphinsdo swim and do splash near our dock. (do swim and do splash have the same helping verb but are two separate verb phrases.) Dolphinsdo 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 Clarenceare talking and eating at the same time. (compound subject and predicate - notice the pattern: subject, subject, verb, verb. Both subjects are doing both verbs.) Samis talking, and Clarenceis 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.)
Practice What You've Learned
Use the toolbar above to underline the subject(s) of each sentence once and the verb(s) of each sentence twice. Do not include the conjunctions. After each sentence, decide if the previous question had a compound subject, compound predicate, or both.