Compound sentences are composed of at least two main clauses. In each clauses (simple sentences), there must be at least a subject and a verb. The following coordinating conjunctions compound the clauses:

and, but, for, nor, or, so, yet

AND:

I love her, and she loves me, too.

BUT:

I’m poor, but I’m happy.

FOR:

She couldn’t pass the exam, for she didn’t study it.

NOR:

I’m not eager to study, nor is she.

OR:

Are you staying at home, or will you come out with me?

SO:

I have passed the exam, so I’m happy.

YET:

She studied hard, yet she couldn’t pass.