U4P4Listeningexercise.ppt

MJ: Hello, Dr Li Yanping. It’s so good of you to talk to me. Some _______ ask us why things always fall back to _____ if you throw them up in the air. Could you ________ it? LY: Well, at first people thought it was because the earth was the ______ of the universe. Of course that was ______. One day Isaac Newton watched an ____ fall to the ground. He said that something else must be ______ the apple back to earth. He called it “gravity”. MJ: I see. Did people _______ his idea? LY: They did. Later they worked out that bigger _______ (like the sun) have stronger gravity than _______ objects (like our planets). If you’re travelling in ____ space, you couldnt fall back to the earth. You’re just too far ______. MJ: Does it mean there’s no ______ in space? LY: No. In a spaceship you would feel the pull as it got ______ to such an object. You would travel faster and faster ________ it. MJ: Until you hit it? LY: Not exactly. You may _____ it very fast and then it would throw you out into space again. After that you would slow down to the _____ speed. MJ: How do you know this? LY: In ____ Einstein said that in space large objects make space-time bend; the larger the object, the ______ space-time bends. So time goes ______ in very strong gravity. MJ: What about ______ holes? LY: That’s a place in space which has such a strong ______ that nothing can escape ____ its gravity. There is a kind of edge around this mass. If you cross over this edge, it’s _________ for you to get back. However if you don’t cross this edge, you can still ______. Stephen Hawking has done a lot of ________ into black holes. He has shown that they “spit” things out as _____ as “eat” them. R: Thank you so much, Mr Yang, for coming to talk to us today about your