16. Jupiter is the biggest planet in our solar system.

• We use "the biggest" because we are comparing Jupiter to all other planets in the solar system, making it a superlative comparison.

17. What is the longest word in English that you know?

• "Longest" is the superlative form of "long" to find the word with the greatest length among all English words.

18. Lions are more dangerous than rabbits.

• We use the comparative form "more dangerous" to compare the danger level between lions and rabbits.

19. That hotel is worse than this hotel.

• "Worse" is the comparative form of "bad" to compare the quality of the two hotels.

20. This chair is as expensive as that chair.

• We use "as...as" to show that the two chairs have the same level of expense.