Distinguishing Between Objects and Complements

To distinguish between direct objects and subject complements, you need to decide if the verb is acting on the object or if the complement is renaming or describing the subject.

We sailed the spaceship out of the atmosphere. - Direct object (We took the spaceship and sailed it.)
Our trip to outer space was exciting. - Subject complement (Exciting describes trip.)

To distinguish between direct objects and indirect objects, you need to decide if you could change the indirect object to a prepositional phrase. Remember, you cannot have an indirect object without a direct object.

Jonas threw the ball. (Only one object, so it must be direct.)
Jonas threw me the ball. Jonas threw the ball to me. (Indirect object because both sentences mean the same thing.)