21. Parents always think that children will get a good job and earn a lot of
      money. 改进: Parents always expect their children to get a good job and
      earn a lot of money.
　　22. If a student only cares about money, will lead to be unhappy all his
      life.
　　改进: If a student only cares about money, he will be misled and will be
      unhappy all his life.
　　23. One purpose of education is to study the way in which he studies later.
　　改进: One purpose of education is to learn to learn.
　　24. Many parents arrange their children go to learn piano.
　　改进: Many parents send their children to piano classes.
　　25. When I want to absorb somebody else’s opinion, I will study with others.
　　改进: When I need second opinion, I will study with others.
　　26. Eating outside has the most advantage that we can go at any time when we
     finish eating without doing any washing.
　　改进: The best part of eating out is that we can leave everything behind
     after meal.
　　27. Smoking can help you relax your mind.
　　改进: Cigarettes can help you relax.
　　28. What’s about nonsmokers?
　　改进: What about nonsmokers?
　　29. Why not to be a non-smoker?
　　改进: Why not be a non-smoker?
　　30. Everyone will have many friends in his life.
　　改进: Everyone has friends in his life.