高中英语人教版必修3 04

[00:06.58]Reading   HOW LIFE BEGAN ON THE EARTH

[00:11.44]After the "Big Bang",the earth was just a cloud of energetic dust.

[00:17.08]What it was to become was a mystery until the dust began to slowly combine

[00:22.41]into a ball moving around the sun.

[00:26.25]The problem was that the earth became violent

[00:30.69]because it was not clear whether the solid shape was to last or not.

[00:36.34]It exploded loudly with fire and rock,

[00:40.83]which were in time to produce the water vapour 1,

[00:44.98]carbon dioxide,oxygen,nitrogen and other gases,

[00:51.33]which were to make the earth's atmosphere.

[00:54.49]As the earth cooled down,water began to appear on its surface.

[01:00.34]Nobody knew that it was going to be different from other planets 3

[01:05.10]going round the sun.

[01:07.74]Water had already disappeared from planets like Mars 4 or satellites like the moon,

[01:15.31]but it stayed on the earth.

[01:18.05]This is how the earth began to show its special qualities.

[01:22.42]Many people think that this was important for the beginning of life.

[01:28.35]It allowed the earth to dissolve harmful gases,

[01:32.71]which had become part of the earth;satmosphere,into the oceans and seas.

[01:40.08]That made it possible for life to begin to develop.

[01:44.23]What scientists think is that the earth was different

[01:48.64]because of the arrival of small plants growing in the water on its surface.

[01:55.49]Nobody understood that these plants were the start of many changes.

[02:01.26]They multiplied and filled the first oceans and seas with oxygen.

[02:08.03]This encouraged the development of early shellfish and all sorts of fish.

[02:14.58]Many millions of years later the first green plants began to appear on land.

[02:20.83]Scientists believe that taking carbon dioxide from the atmosphere

[02:26.78]and filling the air with oxygen helped life to develop.

[02:32.06]Later land animals appeared.Some were insects.

[02:37.41]Others,called amphibians,were able to live on land as well as in the sea.

[02:44.36]When the plants grew into forests,reptiles appeared for the first time.

[02:49.93]They produced young generally by laying eggs.

[02:54.50]Later,some huge animals,called dinosaurs,developed.

[03:00.35]They laid eggs too.

[03:02.70]They became the most important animals on the earth for millions of years.

[03:08.66]But when they they disappeared,mammals became more important.

[03:13.62]They were the last group of animals and they were different

[03:17.77]because they produced their young from within their bodies.

[03:22.03]Small clever animals,now with hands and feet,

[03:26.47]appeared and spread all over the earth.

[03:29.82]They developed new methods of growing food,hunting and moving around.

[03:35.98]As time went by they covered the earth

[03:39.74]and have become the most important animals on the planet 2.

[03:43.69]But they are not taking care of the earth very well.

[03:47.34]They are putting too much carbon dioxide into the atmosphere,

[03:52.70]which prevents heat from escaping from the earth into space.

[03:57.45]The earth may become too hot for the lives on it.

[04:02.31]Whether life will continue on the earth for millions of years to come

[04:05.55]will depend on whether this problem can be solved.

[04:12.81]Using Language  Listening

[04:22.37]1 Look at this information sheet first.

[04:26.74]Then listen to the tape and fill in the chart.

[07:29.70]Reading    A VISIT OT THE MOON

[07:39.44]Last month I was lucky enough to have a chance to make a trip into space

[07:44.77]with my friend Li Yanping,an astronomer 5.

[07:48.43]We visited the moon in our spaceship!

[07:52.19]Before we left,Li Yanping explained to me

[07:57.34]that the force of gravity would change three times on our journey

[08:01.70]and that the first change would be the most powerful.

[08:05.46]Then we were off.As the rocket rose slowly into the air

[08:10.63]we began to feel the pull of the earth,

[08:13.58]which is what we call gravity

[08:16.22]At first it pushed us so hard back into our seats

[08:21.08]that we could not say anything to each other.

[08:24.03]Gradually the weight lessened 6 and I was able to talk to him.

[08:29.49]"Why is the spaceship not falling back to the earth?

[08:33.33]On the earth if I fall from at tree I will fall to the ground."I asked.

[08:39.99]"We are too far from the earth now to feel its pull,"he explained.

[08:45.35]"So we feel as if there is no gravity at all.

[08:49.19]When we get closer to the moon,

[08:51.75]we shall feel its gravity pulling us

[08:55.09]but it will not be as strong a pull as the earth's."

[08:58.85]I cheered up immediately and floated weightlessly around in our spaceship cabin 7

[09:04.81]watching the earth become smaller and the moon larger.

[09:09.49]When we got there,I wanted to explore immediately.

[09:13.53]"Come on,"I said,"If you are right,my mass will be less than on the earth

[09:19.99]because the moon is smaller and I will be able to move more freely 8.

[09:25.03]I might even grow taller if I stay here long enough.

[09:29.08]I shall certainly weigh less!"

[09:31.74]I laughed and climbed down the steps from the spaceship.

[09:35.69]But when I tried to step forward

[09:38.56]I found I was carried twice as far as on the earth and fell over.

[09:43.71]"Oh dear,"I cried,"walking does need a bit of practice

[09:49.98]now that gravity has changed."

[09:52.72]After a while I got the hang of it and we bgean to enjoy ourselves.

[09:58.07]Leaving the mooon's gravity was not as painful as leaving the earth's.

[10:03.82]But returning to the earth was very frightening.

[10:07.35]We watched,amazed as fire broke out on the outside of the spaceship

[10:13.12]as the earth's gravity increased.

[10:16.07]Again we were pushed hard into our seats as we came back to land.

[10:21.32]"That was very exhausting 9 but very exciting too,"I exclaimed 10.

[10:26.68]"Now I know much more about gravity!

[10:30.33]Do you think we could visit some stars next time?"

[10:33.81]"Of course,"he smiled,"which star would you like to go to?"