ex13
1/the stronggest
2/the heaviest
3/the best
4/the most corrodible
5/biggest
6/the most difficult
7/the most damaging
8/the most complicated
ex 15
2/not as light as aluminium
3/not as expensive as gold
4/as easy as copper
5/as a lower as sodium
6/as hard as brass
7/as reactive as carbon
8/as fast as iron