2. more dangerous

3. older/younger

5. more expensive

6. smaller

9. more difficult

Question 1: Which is the highest(high) building in the world?
Question 2: Skateboarding is a dangerous hobby. Bungee jumping is more dangerous(dangerous) than skateboarding.
Question 3: I have three sisters: Jan is the oldest(old) and Angela is the youngest(young).
Question 4: Who has been the worst(bad) singer of the group?
Question 5: This car is certainly better, but it's much expensive(expensive).
Question 6: We live in a small house, but my grandparents' house is even smaller(small) than ours.
Question 7: This factory produced twice as many(many)motorbikes in 2014 as in the year 2012.
Question 8: She is one of the most polite(polite) people I have ever met.
Question 9: People say that Chinese is the most difficult(difficult) to learn than English.