Решение:
- His marks were terrible last year but now they're terriblest (fast) car that they're.
- This is faster we have.
- My mum gets up earlier (early) than anyone else in my family.
- Japanese is more difficult than English.
- This pair of glasses is more expensive (expensive) in this shop.
- Who's youngest (young) person in your family?
- It rained more heavily (heavily) in July than in June.
- He's most careless (careless) student in class.
- I like pineapples least (much) of all fruit.
- Today the weather is worse (bad) than it was yesterday.
Ответ: 1. terriblest, 2. faster, 3. earlier, 4. more difficult, 5. more expensive, 6. youngest, 7. more heavily, 8. most careless, 9. least, 10. worse.