Here are some words and phrases that can help you make a contrast:while, but, howeveron the contrary, in contrast,on the one hand, on the other hand 表达对比和变化的经典句型：表达对比和变化的经典句型：1 过去父母们主要通过写信彼此联系。2 但是现在我们可以在家打长途电话。3 过去我们甚至在周末还要上课。4 现在我不再熬夜，大约10点睡觉。5 在过去的20多年里，我们的生活发生了很大的变化。6 我很高兴告诉你我们 生活的变化。 In the past my parents contacted others mainly by sending letters.But now we call long distance at home.We used to have to attend classes even at weekends.I no longer stay up late, on the contrary, I go to bed at 10 pm.In the past 20 years, great changes have taken place in our life.Im very pleased to tell you the changes in my life.1.In a word, things have begun to improve since last year.2.In short, changes in the past 20 years have broughtus comfort and convenience.3.By 2008, Beijing will become a beautiful, modern and international city.4.The old houses in the central part of the city will be turned into new shopping centers.change, improve, become, turn into老教学楼原操场新操场老教学楼图书馆新教学楼（2001）假设你是李华在一所中学读书。最近收到美国朋友）假设你是李华在一所中学读书。最近收到美国朋友Smith先生的来信，希望了解学校变化情况，给他写回信介绍变化。先生的来信，希望了解学校变化情况，给他写回信介绍变化。-Dear Mr Smith, I was so pleased to hear from you and I am writing to tellyou something about my school. You are right. Quite a fewchanges have taken place. On one side of the road there is a new classroom building. On the other side, where the playground used to be now stands another new building-our library. In it there are allkinds of books, newspapers and magazines. The playgroundis now in front of the school. We have also planted a lot of trees in and around the school. I hope you come and see for yourself some day. Best wishes Yours, Li Hua