单项选择题
A．"How can scientists use machines to look for a star" B．"How far away are the stars" C．"How many years a person would take to go to the next star in a spaceship" D．"Is there life in space"
A．TV can make advertisers aware of their products. B．TV is more popular than any other medium in the United States. C．TV covers a large audience at the same time. D．TV carries more national advertising than other media in the United States.
A．optimistic B．unconcerned C．enthusiastic D．positive