12. Apples are usually cheaper than oranges
.=> Apple are not usually as expensive as oranges 
13. That restaurant is so dirty that no one wants to eat there.
 => It is such a dirty restaurant that no one wants to eat there 
14. Tom is the most industrious pupil.
 => No other pupil is as industrious as Tom
15. She isn't accustomed to life in London.
 => She's not used to life in London 
16. "Don't forget to phone the office," she told him.
 => She reminded him to phone the office 
17. We spent 5 hours getting to London.
 => It took us 5 hours to get to London 
18. I get to work in 20 minutes.
 => It takes me 20 minutes to get to work 
19. She didn't hurry, so she missed the train.
 => If she had hurried, she would have missed the train 
20. Barbara is the best tennis-player in the club.
 => No one in the club is play tennis better than Barbara