Answer:
1. Rio de Janeiro is hotter than London.
2. Siberia is colder than Florida.
3. São Paulo is more crowded than Dublin.
4. Texas is larger than New York.
5. Qatar is smaller than China.
6. San Francisco is better than Los Angeles.
7. Detroit is more dangerous than Boston.
9. Iraq is worse than Iran.
10. Brasilia is safer than Caracas.
Explanation:
When we have a small regular adjective being used to compare, we usually add -er to its ending. If the adjective already ends in -e, we can add only -r. If the adjective has one syllable ending in consonant + vowel + consonant, we must first double the final consonant before adding -er. Examples: hot - hotter; cold - colder; small - smaller; safe - safer.
When the regular adjective is long, we place "more" before it: more crowded; more dangerous.
Irregular adjectives will not follow the rules above, and must be memorized. For example: bad - worse; good - better; far - further.
