Explain the word formation rule demonstrated in the text.

Word Formation Explanation:

• The text demonstrates the use of the prefix 'un-' to form negative adjectives, adverbs, and nouns.
• Examples provided:
• unhappy (adj)
• unlucky (adj)
• unusually (adv)
• uneasily (adv)
• unsafety (n)

Answer: The prefix 'un-' is used to create negative forms of words, indicating the opposite meaning (e.g., happy becomes unhappy).