People build many different kinds of shelter throughout the worlD.The types ofshelters they erect depend16on the climate and on what building materials are17.In hot areas, the weather is warm enough for people to live18much ofthe time. But they still need protection19sun, rain, and insects. Houses there have many screened windows, doors, and other openings that let in breezes but keep out insect pests. In the cool regions, houses are20to keep out the cold and keep in heat. Many buildings have thick walls to21heat loss. In such snowy countries as Norway and Sweden, people build houses with sloping roofs22snow will slide off easily.Building methods and materials23widely throughout the worlD.In regionswith large forests, many people use wood to build homes.24is easy to build with, but most wooden buildings are less sturdy than those made of stone or concrete.In areas with little25, people construct many shelters of clay or muD.InMexico and the southwestern United States, for example, people26clay and dirt or mud with water to make adobe (砖坯). In wet tropical areas,27causes wood shelters to rot within a few years. People in these areas build houses from other materials. For example, in some parts of Africa and on many Pacific islands, people weave the28of tall grass into houses.High-rise buildings made of steel and concrete are most common in suchindustrial countries as the United States and Canada. Prefabricated buildings29parts manufactured at a factory and then shipped to the construction30. There construction workers assemble the parts. Many prefabricated shelters use large amounts of plastic and other lightweight materials.

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