题目

Shopping habits in the United States have changed greatly in the last quarter of the twentieth century. Early in the 1900s, most American towns and cities had a Main Street. Main Street was always in the heart of a town. This street was lined on both sides with many businesses. Here, shoppers walked into stores to look at all kinds of merchandise（商品）：clothing, furniture, hardware（五金）, groceries（杂货）. In addition, some shops offered services. These shops included drugstores, restaurants, shoe-repair stores, and barber or hairdressing shops. But in the 1950s, a change be用面积是1cm2的小正方形量一个大正方形，结果用了9个小正方形，这个大正方形的面积是 cm2．用面积是1dm2的小正方形量一个长方形，结果用了12个小正方形，这个长方形的面积是 dm2．