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) .

如果直放站具有联机调测功能，还可以通过OMT软件对直放站进行工作状态检测、告警检测，以下关于OMT的说法正确的有：（）

A.可以通过OMT软件检测到直放站设置的实际工作增益，要求与设计相符，并与现场测试结果比较，误差范围在正负10%内。

B.可以通过OMT软件检测到直放站实时的输出信号功率，要求与设计相符。

C.可以通过OMT软件检测到当前交流或直流电的供电情况，要求交流工作电压在198V~242V范围内。

D.可以通过OMT软件检测到直放站收发天线的隔离度值。