参考答案:
1. It's been three years since we last saw our primary school classmates.
2. I used to see him reading in the library every day.
3. You can never imagine how difficult the road to success is.
4. He missed his parents so much and he oftenr felt lonely.
5. He became less interested in studying. Sometimes he was absent from classes.
6. Now I understand that even though they are busy, they are always thniking of me.
7. Li Wei's parents now have much more communication with their son than they used to.
8. I know my parents love me and they're always proud of me.
      I have just received a letter from my brother, Tim. He is in Australia. He has been there for six months. Tim is an engineer. He is working for a big firm and he has already visited a great number of different places in Australia. He has just bought an Australian car and has gone to Alice Springs, a small town in the centre of Australia. He will soon visit Darwin. From there, he will fly to Perth.
      My brother has never been abroad before, so he is finding this trip very exciting.