阅读理解
These days, many large city buildings are equipped with their own air-conditioning systems. These systems help keep the buildings cool, but they can also damage the environment. Since they use a lot of electricity, for instance, they contribute indirectly to global warming. In addition, the water that flows through the systems is often cooled using chemicals called chlorofluorocarbons, or CFCs, that are believed to damage the Earth's ozone layer. Recently, though, a system has been built in the city of Toronto, Canada, that cools buildings with little damage to the environment. In the traditional air-conditioning systems found in most large buildings, water is pumped through the building in a continuous cycle. The water is first cooled to a temperature of 4℃ in machines called chillers. It is then sent to individual units that cool the air in each room. As the water flows through the building, it gradually becomes warmer. Finally, it reaches the roof, where it is left to cool down naturally in a water tower. After that it is returned to the chillers, where the cycle begins again. Toronto lies on the shore of Lake Ontario, one of North America' s Great Lakes, and the new system makes use of cold water taken from about 80 meters below the surface of the lake. At this depth, the water in the lake remains at 4℃ all year round. This is exactly the temperature to which the water in air-conditioning systems is cooled. However, the water from the lake is not pumped directly into the air-conditioning systems. Instead, it is used to cool the water that is already inside the air-conditioning systems. After that, the lake water is added to the city's ordinary water supply. Enwave, the company that developed this deep-lake cooling system, says that it uses 75 percent less energy than traditional air conditioning. And since no CFCs are used, no damage can be caused to the ozone layer. Not every city is located next to a large lake, but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.
单选题
What is one problem with traditional air-conditioning systems?
【正确答案】
D
【答案解析】细节题。短文第一段指出传统的空调系统会对环境造成伤害，其中一个危害就是“In addition，the water．．．using chemicals called chlorofluorocarbons…believed to damage the Earth’s ozone layer”，即在水冷却过程中使用的CFCs会破坏地球的臭氧层。故选D。
单选题
What is the function of the chillers in a traditional air-conditioning system?
【正确答案】
B
【答案解析】细节题。短文第二段指出“The water is first cooled to a temperature of 4℃ in machines called chillers．”，即chiller的作用就是制冷。故选B。
单选题
What happens in the end to the water from Lake Ontario?
【正确答案】
A
【答案解析】细节题。短文第三段最后指出“After that，the lake water is added to the city's ordinary water supply．”，即湖水最后应用到城市居民用水中。故选A。
单选题
What is one advantage of Enwave' s new system?
【正确答案】
C
【答案解析】细节题。短文最后一段第一句指出“Enwave…deep-lake cooling system，says that it uses 75 percent less energy than traditional air conditioning.”，即与传统的空调系统相比，Enwave公司设计的这种新的制冷系统使用的能源要少75％，由此可知，选项C正确。
单选题
Which of the following is true?
【正确答案】
B
【答案解析】细节题。根据短文第三段中“At this depth，the water in the lake remains at 4℃ all year round.”可知选项B正确。根据短文最后一句“but experts believe that systems like the one being used in Toronto could be built elsewhere by using other natural sources of cold water.”可知选项A、D错误；根据短文第二、三段可知Enwave’s system不使用CFCs，故排除C。所以选B。