Final answer:
The King of Brobdingnag forms a negative opinion of English society, thinking of them as harmful and detestable, due to Gulliver's descriptions of its flaws and injustices.
Step-by-step explanation:
The King of Brobdingnag concludes that English society must be "the most pernicious race of little odious vermin that nature ever suffered to crawl upon the surface of the earth" after Gulliver describes it to him.
He forms this opinion because Gulliver highlights the flaws and injustices in English society, such as political corruption, war, and mistreatment of others.
Gulliver's descriptions paint a negative picture of English society, leading the King to view the English as a harmful and detestable race.