听力原文： Advertising actually has a dual function: to sell, as well as to inform. If you stop to think of it, advertisements pro vide information of almost everything in our household and immediate environment, from shampoo to fuel for cars. A significant purpose is to inform. consumers of new products and new services as well as to remind them of established ones. Performance, price, value for money, quality and reliability are some of the main features mentioned in advertisements. Yet there is another important aspect of advertising that should not be forgotten: that of choice. A number of advertisements for different brands of the same product, e.g. toothpaste, shampoo or washing powder allow the consumer to choose. Choice is an important part of buying. In this busy day and age, there is little time for comparison shopping. To determin which product is the best to buy, and at the most competitive price, consumers these days rely on advertising in its various forms. This saves time and energy and simplifies shopping. So for busy people like you and me, advertisements actually do us a favor. What is the dual function of advertisements?