5. Scientific Discovery — Curse Or Blessing
New scientific discovery nearly always brings mankind a blessing. Take electricity for example. Since its discovery, it has ushered in an era of countless inventions in close connection with it. Nowadays people can read and write by means of lights instead of candles. Fire is another example of discoveries which made human beings survive in ancient times and generates electricity in modern times. Again, minerals such as oil or coal discovered by man have long been used as fuel to develop industry and agriculture.
Yet sometimes scientific discoveries may prove a curse upon the human race. As we know, everything has two sides. Electricity can shock one to death if used carelessly. Smoke from factories and gases from cars are terrible pollutants. Radium used in nuclear power plants can lead to a nuclear war.
The misuse of scientific discoveries must be prevented. Since chemical elements or substances were discovered, some have been made use of for purpose of war. Such weapons as atomic bombs or poisonous gases have proved to be destructive to mankind. Therefore, it is the whole world's duty to prevent scientific discoveries from menacing the human race.

6．Internet — A Two-edged Sword
Internet is playing an increasingly important role in people's life. As a newborn information delivering system, the Internet has made seas of information available at our fingers’ tips. Besides, the Internet serves as the most convenient means for communication. Through the Internet, people can discuss various problems and make friends who share common views.  
But just as a coin has two sides, Internet has its own drawbacks which should not be neglected. First, it costs an alarming amount of money to construct the system and the cost is very high to most Chinese consumers. Second, it is sometimes difficult for people to find the right information they are looking for since there is too much rubbish on the net. Finally, it is also difficult to prevent the net from the invasion of criminals.
Therefore, the Internet should be viewed as a two-edged sword, which presents us with both conveniences and troubles. But we should not give up eating for fear of choking. The best policy, as I see it, is to further develop the net and exert proper supervision over it so that it can benefit us in a better way.

7．The Greatest Invention in the Past Century
When asked about the greatest invention in the past century, some people may claim that it is the computer; others may say it is the mobile phone; still others may say it is the automobile. In my opinion, however, it is the Internet.
Of course, the computer, or the electric brain, has greatly facilitated our mental work and spare us the burden of calculating, restoring and searching; the automobile saves us time and makes our travel more convenient and the mobile phone has got people closer. But, these are just the extension of human brain, legs and voice. The Internet, however,  has changed human life in a more fundamental way since its birth.