阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

People have lived in cities for thousands of years. Yet even just 100 years ago, more people 【小题1】 (live) in the country than in cities. Today, with the population in the world 【小题2】 (increase) sharply, more people move to cities for various 【小题3】 (reason). For many it is for work or education. Some are 【小题4】 (simple) attracted to city life. By the year 2030, it is thought 【小题5】 more than sixty percent of the world's population will be living in cities. More and more cities will become megacities (特大城市), and they will 【小题6】 (find) in different parts of the world.

Maybe one megacity is not the same as another 【小题7】 they do have common problems, such as air 【小题8】 (pollute), housing problems, traffic jams and so on. Making these cities work well for every person living in them will be 【小题9】 great challenge in the future. However, we do believe when people work together, they can find solutions which will help make these megacities happy, healthy and 【小题10】 (excite) places to live in.