Advertising gives useful information about which products to buy. But modern advertising does more than gives news about products and services. Today's advertisements, or ads, try to get consumers to buy certain brands. Writers of advertising are so skillful that they can, sometimes persuade a consumer to wear a certain kind of clothing, eat a special kind of cereal, or see a movie. Consumers might never even want a product if they did not see or hear advertisements for it. For example, you probab1y do not need the newest cereal in the supermarket. There are probably many cereal brands on your kitchen shelves. You may not have space on a shelf for another. But if you see ads about a new cereal that is your extra-tasty and has a free prize in the box, you may want it. Advertising must get attention. To be effective, it must be exciting, entertaining, or provide some pleasure. The secret of writing good advertising copy is to offer a good idea as well as a product. The idea is what the ad is really selling. One example is an ad that says eating a certain cereal will make a person do well in sports. That cereal brand may sell better if consumers think it offers strength and energy. From the passage, we know that   _   .
modern advertising has less effect on customers once customers see ads about a new cerea1, they are sure to buy it cereal can make people strong cereal is a kind of food which is popular among people