Several years ago ,Masaru Ibuka ,chairman of Sony ,was at a company planning a meeting. Suddenly he hdd a brilliant idea. He stopped the meeting and asked everyone present what would happen if Sony removed the recording function and 'speaker and sold headphones with a tape player instead. Almost everyone thought he was crazy. Still ,Ibuka kept thinking about his idea and worked at improving it The result, of course, turned out to be the wildly successful Sony Walkman. Good ideas often start with a seemingly silly question. Bill Bowerman was making breakfast one day. As he stood there making waffles  for his son, he wondered what would happen if he poured rubber into his waffle iron. Later ,he tried it and the result looked something Like the bottom of most sports shoes we see today. Still, when he took this idea to several existing shoe companies, he was laughed at In fact, every single company turned him down. Though rather discouraged, Bowerman insisted and went on to form his own company, making NBKE athletic shoes. Sometime good ideas grow out of frustration  .When Fred Smith was a student at Yale University, he had some paperwork that he needed to have delivered across the country the next day. Smith was amazed to find out that overnight delivery was impossible. He sat for a long while ,lost in thought Why couldn't there be a reliable overnight mail delivery service? He decided to design one. Smith did just that and turned his design into a class project His business professor gave him only a C for his efforts. However, Smith was not through. He improved the idea in that class project and finally turned them into one of the first and most successful overnight mail service in the world -- FedEx. We know that each of these ideas led to a very successful product or service that has changed the way many of us live. The best questions are usually open-ended and are often silly, Children aren't afraid to ask such questions ,but adults frequently are. Think how different the world might be if people never asked " silly" questions! The passage is mainly developed by  _  .
analyzing possible reasons presenting different opinions providing typical examples listing practical suggestions