다음 글의 주제로 가장 적절한 것은? Dubai is one of the hottest and driest places on earth. In the past, there was no air-conditioning, or even electricity. How did people in Dubai survive in this severe weather? They invented a type of air-conditioning that did not require electricity: the wind tower. A wind tower stands tall above a house. It catches the wind and moves it inside. The air is cooled down when it meets cold water that flows through the underground canal in the building. This air cools the inside of the building. The buildings are made with thick walls and have small windows; these help keep cool air in and heat out. Most houses are built very close together with high walls and ceilings. This also helps create more shade and reduce heat. Although modern buildings in Dubai are air-conditioned and no longer use wind towers for cooling, wind towers still remain an important architectural symbol in Dubai.