30. Gary is the best guitarist in her class.
→ No one else is better guitarist than Gary
31. Since the invention of computer, people have saved a lot of time.
→ Since the computer was invented, people have saved a lot of time.
32. It's necessary for everybody to clean up their neighborhood once a week.
→ Everybody should clean up their neighborhood once a week.
33. It may rain hard this afternoon, so take the raincoat with you.
→ In case hard rainy this afternoon, so take the raincoat with you.