A、The commercials both on TV shows and on billboards are fun. B、They both have a beginning, a middle, and an end with commercial

Long bus rides are like television shows. They have a beginning, a middle, and an end-with commercials thrown in every three or four minutes. The commercials are unavoidable. They happen whether you want them or not. Every couple of minutes a billboard glides by outside the bus window. Your sleep is equal to turning the television off. The beginning of the ride is comfortable and somewhat exciting, even if you’ve traveled that way before. Usually some things have changed- new houses, new buildings, sometimes even a new road. The bus driver has a style of driving and it is fun to try to figure it out the first hour or so. If the driver is particularly reckless, the ride can be as thrilling as a suspense story. Sleeping for a while helps pass the middle hours of the ride. Food always makes bus rides more interesting. But you’ve got to be careful of what kind of food you eat. Too much salty food can make you very thirsty between stops. The end of the ride is somewhat like the beginning. You know it will soon be over and there’s a kind of expectation and excitement in that. The seat, of course, has become harder as the hours have passed. By now you’ve sat with your legs crossed, with your hands in your lap, with your hands on the arm rests- even with your hands crossed behind your head. The end comes just at the right time. There are just no more ways to sit.
Questions 16 to 18 are based on the passage you have just heard.
16. Why does the speaker feel long bus rides are like TV shows?
17. How do we spend the middle hours of the ride according to the passage?
18. What is the purpose of this passage?