Today"s lecture is about the mass 1 of the world"s population. There are two major 2 why people are moving to cities. The first reason is 3 . People are moving to the cities because that"s where they can find 4 and earn money. The second reason for the move to cities has to do with 5 of life issues: comfort and 6 . Cities often offer better 7 . And then for many, city life is just more 8 . An interesting consequence of urbanization is that the average 9 of people in the countryside is increasing, while that of the cities is 10 .
Three key 11 can be identified in our cities. First of all, they"re getting bigger. Most cities are bigger now than ever before. Cities are also changing shape. They"re getting 12 , because land is getting more and more expensive. 13 have become a symbol of modern cities.
Cities are also changing shape in other ways. The 14 Model and The 15 Nuclei Model are probably more typical of the cities we know today. They show the urban 16 that"s occurring in contemporary cities.
The third change is that our cities are breaking up into 17 communities, often by 18 group or 19 level. This often means that people stay within their community and do not come into contact with others from different 20 .