1 more interesting
2 the least
3 harder and harder
4 the most tiring
5 the happiest
6 the more - the better
7 easier
8 much more
9 longer and longer
10 more hard-working
11 the longest
12 the friendliest
13 friendlier
14 the worst
15 freer
16 faster
17 the most quietly
18 higher
19 more deeply / deeper
20 later / latter
