A compound sentence has two or more independent clauses in it. Every compound sentence will have either a FANBOYS in it or a semi-colon which joins the two clauses. If a FANBOYS is used, it must be preceded by a comma. A compound sentence will never have a dependent clause in it.
- Jeb drove to the accidentally drove into a tree.
- I love does not.
- My wife is a very avid decided to purchase a commercial duty mixer for her.
The following sentence is simple. The reason it is not compound is that both verbs “went” and “forgot” are governed by the same subject “Jeb”. Hence, there are not two independent clauses here but only . Notice also that there is no comma.
Jeb went to the store yesterday to get some milk but forgot to purchase some Canola oil.