Here's why:
* Direct objects receive the action of the verb. They answer the question "What?" or "Whom?" after the verb.
* "To finish your test" is an infinitive phrase acting as the object of the preposition "to."
Let's break down an example:
Sentence: I want to finish your test.
* Verb: want
* Object of the preposition "to": to finish your test
In this sentence, "to finish your test" is not directly receiving the action of "want." Instead, it's the thing you want to do.
To find the direct object, ask "What does the verb 'want' act upon?"
The answer is "I" want something. There is no direct object in this sentence.