例如：
Books are like friends. They can help us know the world better, and theycan open our minds and widen our horizons. Therefore, reading extensively is ofgreat benefit to us.
三、表示坏处
1. It has more disadvantages than advantages.
2. It does us much harm.
3. It is harmful to us.
例如：
However, everything divides into two. Television can also be harmful to us.It can do harm to our health and make us lazy if we spend too much time watchingtelevision.
四、表示重要. 必要. 困难. 方便. 可能
1. It is important(necessary, difficult, convenient, possible. for sb. todo sth.
2. We think it necessary to do sth.
3. It plays an important role in our life.
例如：
Computers are now being used everywhere, whether in the government, inschools or in business. Soon, computers will be found in every home, too. Wehave good reason to say that computers are playing an increasingly importantrole in our life and we have stepped into the Computer Age.
五、表示措施
1. We should take some effective measures.
2. We should try our best to overcome (conquer. the difficulties.
3. We should do our utmost in doing sth.
4. We should solve the problems that we are confronted(faced. with.
例如：
The housing problem that we are confronted with is becoming more and moreserious. Therefore, we must take some effective measures to solve it.
六、表示变化
1. Some changes have taken place in the past five years.
2. A great change will certainly be produced in the world’scommunications.
3. The computer has brought about many changes in education.