The predicate is the part of the sentence that makes a statement about the subject. The predicate usually tells us what the subject is doing or what is happening to the subject.
A compound predicate tells us two (or more) things about the same subject (without repeating the subject).
This is a simple predicate:
Adam lives in Bangor.
(This tell us just one thing about the subject (Adam). This is not a compound predicate.)
Examples of Compound Predicates
These are examples of compound predicates:
Adam lives in Bangor and speaks Welsh.
(This tell us two things about the subject (Adam).)
The telegram was late but contained exciting news.
They need to absorb nitrogen and keep above 20 degrees.
There Is One Subject in a Compound Predicate
A compound predicate tells us at least two things about one subject. So, the following sentence is not an example of a compound predicate:
Adam lives in Bangor, and he speaks Welsh.
(This is a compound sentence. It has two subjects (Adam and he). Each subject has one simple predicate.)
The following sentence is an example of a compound predicate:
Adam and his brother live in Bangor and speak Welsh.
(The predicate tell us two things about the subject (Adam and his brother). Even though it has two elements, this is one subject. It is called a compound subject.)
There is often confusion over whether to use a comma before a conjunction (i.e., a word like and and but).
It is worth being able to spot a compound sentence because you should use a comma before a conjunction that joins two independent clauses. For example: