参考例文：
Dear Mary，
This city has changed a lot in the past 5 years. First，more high buildings have appeared，which are modern and beautiful. Many overpasses have been set up，so it has become very convenient for people to travel. Besides，many families have got cars of their own. The people's life here has become rich and colorful. People can enjoy themselves travelling on holidays. To my delight，I can taste delicious food of different countries such as the food of America，Japan and South Korea. And now it is easier for me to keep in touch with you than last time，for I can email you in my office.