A、They will become inactive and dull. B、They will not go to cinemas as often. C、They will forget to do their homework. D、They wi

Children in the United States are exposed to many influences other than that of their families. Television is the most significant of these influences, because the habit of watching television usually begins before children start attending school. And, by the time that the average child finishes high school, he or she will have spent 18,000 hours in front of a television set as opposed to 12,000 hours in a classroom.
    Parents are concerned about these figures. They are also concerned about the lack of quality in television programs for children. The degree of violence in many of these shows also worries them.
    Even if it is unreal — a cartoon cat beating up a cartoon mouse with a baseball bat — this violence may have a negative effect on the young minds exposed to it. Studies indicate that, when children are exposed to violence, they may become aggressive or insecure.
    Parents are also concerned about the commercials that their children see on television. Many parents would like to see fewer commercials during programs for children. And some parents feel that these shows should not have commercials at all because young minds are not mature enough to deal with the claims made by advertisers.
    Educational television has no commercials and has programs for children that many parents approve of. The most famous of these is "Sesame Street", which tries to give preschool children a head start in learning the alphabet and numbers. It also tries to teach children useful things about the world in which they live.
    Even though most parents and educators give "Sesame Street" and shows like it high marks for quality, some critics argue that all television, whether educational or not, is harmful to children. These critics feel that the habit of watching hours of television a day turns children into bored and passive consumers of their world rather than encouraging them to become active explorers of it.
Questions 16 to 18 are based on the passage you have just heard.
16. What is the main idea of the passage?
17. According to the passage, what do you think "Sesame Street" is?
18. What will be the consequence if a child forms a habit of watching hours of television every day?