写作思路：

　　20、不同意，儿童应当长在大城市

　　(1)大城市能让儿童受到良好的教育

　　(2)大城市能够让儿童开阔视野，接触到很多东西。

　　(3)大城市的娱乐更多，儿童更喜欢

　　(4)大城市的医疗设备比较好，儿童得病可以得到迅速治疗

　　参考范文：

　　There are advantages and disadvantages to a childhood in either the country or a city. It's hard to say which is better. Growing up in the country means a certain amount of isolation. You're in a small town or on a armband not with a lot of people. Even more important, the people you meet everyday tend to be just like you. Most will be the same race as you, have the same background as you, and will have gone to the same school as you. In the city, the people you meet are different. There are different races and different cultures. You get a more interesting mix.

　　City people tend to come from a lot of different places and move around a lot. So, there isn't the sense of community in the city that you have in the country. People in the city can live in the same apartment building for twenty years and never get to know their neighbors. In the country, everybody knows everybody. For a child, this means the country is more secure. A child can get lost or hurt in the city and have no one to turn to. In the country, everyone’s a neighbor. People in the country feel connected to each other.

　　A child growing up in the city has the advantages of a lot of interesting and exciting place to visit. He or she can go to the zoo, museum, art galleries and concerts. There are a lot of restaurants with different kinds of food. It’s easy to see every new movie that comes out. Child in the country don't have a lot of these activities nearby.

　　All in all, I think a childhood in the city is better because it prepares you more for what real life is like.