Read the following article and answer the question. Article: Art museums are places where people can learn about various cultures. The increasingly popular "design museums" that are opening today, however, perform quite a different role. Unlike most art museums, the design museum shows objects that are easily found by the general public These museums sometimes even place things like fridges and washing machines in the center of the hall Pele have argued that design museums are often made use of as advertisements for new industrial technology. But their role is not simply a matter of sales-it is the honoring of excellently invented products. The difference between the window of a department store and the showcase in a design museum is that the first tries to sell you something, while the second tells you the success of a sale. One advantage of design museums is that they are places where people feel familiar with the exhihits. Unlike the average art museum visitors, design museum visitors seldom feel frightened or puzzled. This is partly because design museums clearly show how and why mass-produced products work and look as they do, and how design has improved the quality of our lives. Art museum exhibits, on the other hand, would most probably fill visitors with a feeling that there is something between their understanding. In recent years, several new design museums have opened their door. Each of these museums has tried to satisfy the public's growing interest in the field with new ideas. London's Design Museum, for example, shows a collection of mass-produced objects from Zippo lighters to electric typewriters to a group of Italian fish-tins. The choices open to design museums seem far less strict than those to art museums, and visitors may also sense the humorous part of our society while walking around such exhibits as interesting and unusually attractive toys collected in our everyday life. Question: Showcases in design museums are different from store windows because they _ . Answer:
show why the products have sold well