Final answer:
Lily should use a thesaurus to find synonyms for repetitive words, while John should consult a dictionary to ensure correct word usage in their essays.
Step-by-step explanation:
To address Lily's issue of using repetitive, boring words in her essay, she could use a thesaurus. A thesaurus provides synonyms and can help her find more varied and dynamic words to express her ideas, thus enhancing her vocabulary and the overall quality of her writing.
As for John, who used words inaccurately, a dictionary would be the most helpful tool for him. A dictionary provides definitions and usage examples that can aid John in selecting the correct words to precisely convey his intended meanings in the essay.