Teachers help you focus on what you're learning. If you're learning something by yourself, it’s easy to become distracted, and go on to other activities. Teachers keep your attention on the subject. They also approach a subject logically, taking it one step at a time. On your own, it's tempting to skip parts of the learning process you think you don’t need. That can binder your ability to really understand the subject.

　　Learning a subject on your own is a very narrow way of learning. You can only use the information you get from the textbook. With a teacher, you get the information in the written materials as well as the teacher's own knowledge of the topic. Teachers can also provide extra materials to broaden the scope of what you're learning.

　　There's nothing wrong with studying on your own, and a learner can always benefit from some quiet study. For the best possible learning, though, a good teacher is the biggest help you can have.

　18 What are some important qualities of a good supervisor(boss)? Use specific details and examples to explain why these qualities are important.

　　Even though job situations can be very different, there are several qualities that all good supervisor have in common, A good boss treats all her employees fairly. She doesn't single out one employee for better(or worse)treatment than the others. A poor supervisor has favorites. Sometimes she'll even use her favorites to spy on other employees. She expects them to tell her what the others are saying about her. This can cause a lot of bad feeling among employees.

　　A good supervisor gives clear and understandable directions. She doesn't constantly change her mind about what she wants employees to do. She also doesn't get angry with an employee who is confused and needs her to explain the directions again or more fully. Delegating authority well is another quality of a good supervisor. She knows how to use the skills of her employees to best advantage. A poor supervisor insists on doing everything herself. She is unwilling to give any authority to others.

　　A good boss evaluates her employees on a reasonable ser of criteria, not on how she feels about them personally. And she lets the employees know what those criteria are, so they have a fair chance of meeting them.

　　She gives both praise and criticism in a straightforward manner. She also offers guidance when needed. A poor supervisor will criticize without giving any suggestions on how to improve.

　　Most importantly, a good supervisor set the standards for her employee by her own behavior. She works hard and treats employees like valuable assets to the company. This promotes good morale among her workers, and this is of great benefit to her business.

　　19 Should governments spend more money on improving roads and highways, or should governments spends more money on improving public transportation ( buses, trains, subways)? Why? Use specific reasons and details to develop your essay.