Here are the completed sentences with the appropriate forms of the words in brackets:

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 **more 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 politest** (polite) people I have ever met.
Question 9: People say that Chinese is **more difficult** (difficult) to learn than English.
Question 10: She is **the most beautiful** (beautiful) girl I have ever met.
Question 11: Our hotel was **cheaper** (cheap) than all the others in the town.
Question 12: Potential dehydration is often **the greatest** (great) hazard that a land animal faces.
Question 13: In the last holiday I read a good book, but my father gave me an even **better** (good) one last weekend.
Question 14: I bought **the cheapest** (cheap) shirt of the shop.
Question 15: School is boring, but homework is much **more boring** (boring).
Question 16: A park bench is comfortable, a restaurant chair is **less comfortable** (comfortable), but a sofa is **the most comfortable** (comfortable).
Question 17: Yesterday John told me a funny joke. This was **the funniest** (funny) joke I've ever heard.
Question 18: Here is Emily. She's six years old. Her brother is nine, so he is **older** (old).
Question 19: My sister was **the smallest** (small) girl in her classroom.
Question 20: This museum has got **the largest** (large) collection of antique objects in the world.