4）it is beneficial to us．
5）it is of great benefit to us．
例如：
books are like friends．they can help us know the world better，and they can open our minds and widen our horizons．therefore，reading extensively is of great benefit to us．
3．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 watching television．
4．表示重要、必要、困难、方便、可能
1）it is important（necessary，difficult，convenient, possible）for sb．to do 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，in schools or in business．soon, computers will be found in every home，too．we have goo