填空题 There"s good news and bad news about life in modern cities—first, the bad. People who study population growth predict a nightmare by the year 2025: the global population will be more than 8 billion, and almost 4 billion of these people will be living in cities in developing countries such as India and Nigeria. Population growth is already causing unbelievable overcrowding. Nairobi, Kenya, has basic services for 200,000 people but has a population of 5 million. Mexico City is home to almost 25 million people. By the year 2025, population experts predict, 660 million people will be living in cities in India. Due to overcrowding, these cities have problems with air pollution, disease, and crime. People spend hours in gridlock—that is, traffic so horrible that it simply doesn"t move—when they commute daily from their homes to their work and back. There isn"t enough water, transportation, or housing. Many people don"t have access to health services or jobs. Now the good news: in some cities, instead of worsening, urban life is actually getting much better.