Ответы и объяснения

 cleaner; the cleanest
earlier; the earliest
nicer; the nicest
worse; the worst
more boring; most boring
elder; the eldest
more famous; most famous
better; the best

1) they discuss; get - не уверен
2) She will be preparing everything by 5 o'clock; will wait 
3) said; had sent
4)  don't fallen (haven't fallen); heard
5) I know Sam well
6) we have lived there for ten years.
7) when we are leaving the cinema, we saw our friends
8) Tomorrow It will be rain.
9) are
10) he has just cooked supper
11) lost; looked for
12) Did the rain yesterday?
13) Next week we are playing hockey. или Next week we will play hockey
14) will return; will want to know; will be - в этом предложении не уверен