教材习题点拨
COMPREHENDING
Answer key for Exercise 1：
Paragraph 1：A widely accepted theory about the formation of the universe
Paragraph 2：The formation of the earth
Paragraph 3：The importance of water for life
Paragraph 4：The development of plants and animals on the earth
Paragraph 5：The arrival of humans and their impact on the earth
Answer key for Exercise 2：
10 7 3 8 4 9 6 1 5 2 12 11
Answer key for Exercise 3：
1 Because the water remained on the earth.
2 Because plants provide oxygen for animals to breathe.
3 Because dinosaurs died out long before human beings developed on the earth.
4 The name is Pluto.Scientists now think it is too small to be called a planet.
5 Human beings caused global warming.
Suggested answers to Exercise 4：
Discourse markers：
however，after that，next，later，finally，thus，as a result of
Sentence connectors or conjunctions：
and，but，because
Suggested answers to Exercise 5：
The other puzzles hidden in the passage are：
How did the earth's atmosphere develop?
Why did water stay on the earth but not on the other planets?
How did life forms develop?
Why did some life forms disappear?
LEARNING ABOUT LANGUAGE
Discovering useful words and expressions
Answer key for Exercise 1：
(en)ce | un | ||
present violent confident different patient | presence violence confidence difference patience | certain fair paid like kind | uncertain unfair unpaid unlike unkind |
al | ist | ||
culture globe universe agriculture mathematics | cultural global universal agricultural mathematical | art physics chemistry biology science | artist physicist chemist biologist scientist |
Answer key for Exercise 2：
1C 2A 3C 4B
Answer key for Exercise 3：
fundamental，astronomy，gave birth to，existed，As a result，atoms，from，puzzle
Emotional words | Calm words |
violent angry give a personal reactionrude shocked excited crazy | patient gentle relaxing kind easygoing calm |
Discovering useful structures
Answer key for Exercise 2：
1 What has not yet been proved is his discovery.
2 Whether the other astronomers accept his ideas remains a question.
3 How life first appeared on earth is still a mystery to scientists.
4 Why the earth is becoming warmer is an important topic for research.
5 It amazed everybody that Stephen Hawking at 65 experienced zero gravity during a flight.
6 It is a surprise that Pluto is no longer considered a planet in our solar system.
Suggested answers to Exercise 3：
1，4，3，5，2，6
USING LANGUAGE
Listening and discussing
LISTENING TEXT
THEORIES OF GRAVITY
Michael Jones of the New Space Magazine is talking with space traveller Li Yanping about changes in the theory of gravity.
LY＝Dr Li Yanping MJ＝Dr Michael Jones
Part 1
MJ：Hello，Dr Li Yanping.It's so good of you to talk to me.Some students ask us why things always fall back to earth if you throw them up in the air.Could you explain it?
LY：Well，at first people thought it was because the earth was the centre of the universe.Of course that was wrong.One day Isaac Newton watched an apple fall to the ground.He said that something else must be pulling the apple back to earth.He called it “gravity”．
MJ：I see.Did people accept his idea?
LY：They did.Later they worked out that bigger objects(like the sun)have stronger gravity than smaller objects(like our planets)．If you're travelling in deep space，you couldn't fall back to the earth.You're just too far away.
Part 2
MJ：Does it mean there's no gravity in space?
LY：No.In a spaceship you would feel the pull as it got closer to such an object.You would travel faster and faster towards it.
MJ：Until you hit it?
LY：Not exactly.You may pass it very fast and then it would throw you out into space again.After that you would slow down to the usual speed.
MJ：How do you know this?
LY：In 1905 Einstein said that in space large objects make spacetime bend；the larger the
object，the further spacetime bends.So time goes slower in very strong gravity.
MJ：What about black holes?
LY：That's a place in space which has such a strong mass that nothing can escape from its gravity.There is a kind of edge around this mass.If you cross over this edge，it's impossible for you to get back.However if you don't cross this edge，you can still escape.Stephen Hawking has done a lot of research into black holes.He has shown that they “spit” things out as well as “eat” them.
Answer key for Exercise 2：
Summary B is correct because it gives a clear idea of what the listening passage is about.
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