7 - These trainers are much cheaper than those. (cheap)
8 - Frank works harder than most people (hard)
9 - I'm better at English than you. (good)
10 - Today has been the hottest day of the year. (hot)
11 - This is the worst CDI've ever listened (bad)
12 - English is easier than Japanese, (easy)
13 - Which mountain is the highest in the world. (high)
14 - Fohn is cleverer/more clever than his brother. (clever)
15 - English is more useful than Latin. (useful)