1-better
2-the fastest
3-bigger
4-more difficult
5-the most expensive
6-the youngest
7-heavier
8-the most careless
9-more
10-worse
№ 3
You must be quiet.
You mustn't eat or drink in the library.
You must be careful with hte books.
You mustn't leave the books on the table when you leave.
You must put the books back in the right place.
№ 3
2-mustn't
3-must
4-must
5-mustn't
6-mustn't
7-must
8-must