A、A billion. B、Over 450. C、Hundreds of billions. D、Hundreds of millions. B文中提到近年来发现了450多颗行星，这些行星围绕着距离地球十分遥远的恒星运行，因此地球外存在生命的可能性随之

John Smithson, one of the executive producers, talking about Hawking, told AOL News from his London office. "(9)It was pretty hard because you’re dealing with one of the most brilliant people in the world, and you’re dealing with some of the most complex things imaginable," he says. "There’s so much we know about the universe and there’s so much we don’t know. That’s why it’s good there can be vigorous debate, because we simply don’t know the answers to many of these questions," Smithson says.
     (10)The possibility of life outside our earth has increased in recent years with the discovery of more than 450 planets in orbit around faraway stars. It would make a lot of sense to consider that life may be abundant in the universe. After all, we know there are billions of galaxies out there in the universe, with each galaxy made up of hundreds of millions of suns.
    Hawking doesn’t dismiss the importance of people on earth venturing out into space. Smithson says. "He’s a very philosophical guy. I know he is totally for the continuation of space exploration. He believes it’s absolutely vital for the human race to keep on exploring our universe. " And yet,(11)Hawking is still pessimistic about trying to make friends with an alien species. "If aliens ever visit us, I think the outcome would be much as when Christopher Columbus first landed in America, which didn’t turn cut very well for the native Americans. "
Questions 9 to 11 are based on the conversation you have just heard.
9. What did John Smithson say about Hawking?
10. How many planets have scientists discovered in recent years?
11. What’s Hawking’s attitude towards outer space aliens?