Ответ:

Ex. 2.

1) than

2) the smallest, in the world

3) as clean as

4) of

5) in

6) than

7) in

8) as noisy as

Ex. 3.

1) more expensive

2) more crowded

3) as high as

4) the oldest

5) the largest

6) cheaper

7) the tallest

8) more polluted

9) the best

10) smaller