For some reason, Merriam-Webster’s 11th Collegiate gives both transitive and intransitive definitions for ravage in its use as a verb. I can’t imagine using it without a direct object. In any case, here is a context clues worksheet on the verb ravage. It’s in common enough usage in the English language that high school students ought to know it.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.