1.越来越多的人涌入大城市，有些问题随之产生。
2.比较明显的大问题有......
3.我对这种现象的想法。
城市问题(City Problems)
Nowadays, millions of migrant workers flock into cities in search of jobs and better living. However, with the sharp rise in the urban population,many problems arise in the development of cities.
Firstly, cities become more and more crowded, putting much pressure upon transportation, housing, sanitation, education, employment and so on. City services and facilities have been strained to a breaking point. Secondly, a growing number of private cars emit huge amount of carbon dioxide, leaving the air mercilessly polluted. What is more, the city is also threatened by rising crime. Not a single day passes without the report of someone being robbed, kidnapped or murdered. Last but not least, city-dwellers are not only separated from the natural world but also isolated from each other, even not knowing the name of their next-door neighbor.
All these problems have harmed the attractiveness of the city. Unless there is some improvement, more and more people may seek to live in the suburbs.