单项选择题
【案例分析题】
Big cites today are confronted with very serious problems.Transport is a【C1】______difficulty：some planners believe in【C2】______transport system；others believe in making it possible for citizens to move【C3】______in private cars.There are several ways of【C4】______a public transport system.Sometimes it is built under the ground，sometimes it is on the【C5】______，and sometimes it is even above ground level，【C6】______in parts of New York and more crime and Tokyo for example.In most cases，of course，it is a【C7】______of some or all of these elements.The【C8】______of the city centers has also been a problem in the last 30years.The hearts of many cities have become poorer and poorer，【C9】______more and more crime and violence，【C10】______the people who can afford to have moved out to the【C11】______.This is the opposite of the situation 100years a-go，【C12】______wealthypeoplelivedinthecenter，and the poor lived【C13】______the outskirts of the city.Ecological problems also【C14】______，as factories and cars pollute the air.tree are cut down to make【C15】______for urban clearways，and crowded conditions cause garbage to【C16】______in the streets.In order to solve these problems，some planners believe we should limit the size of our cities，perhaps by restricting population，or perhaps by offering【C17】______jobs in the provinces.Others believe that cities cannot be limited in size and that the problems must be solved in a【C18】______of ways—by creating green areas，building【C19】______houses for everybody，stopping factory pollution.【C20】______motor transport，and so on.
【C1】（）
