=>

1. answering -> answer

2. produced -> has produced

3. for -> to

4. for -> to

5. for -> to

6. listening -> listen/surfing -> surf/ chatting -> chat

7. changed -> has changed

8. since -> for

9. meet -> meeting

1. IBM is an artificial intelligence computer system and is used to answering questions posed in natural language 
2. Kodak Company produced many OLED equipped products, which are being used to power the next generation of ultra-thin televisions, since 1987
3. Vaccination has been used for a long time to prevent (Hoặc for preventing) diseases
4. The boat rudder was invented to steer large ships, which enabled the Chinese for building huge ships as early as 200 AD
5. Many young people now use computers for playing games rather than study
6. You can use a tablet to listening to music, surfing web or chatting with friends
7. Since the Internet was first created in the 1960s, it changed people's lives a lot
8. Scientists have researched since years into ways of curing cancer patients
9. Many teenagers now prefer chatting on the computer to meet face to face