最新人教版英语必修3 unit4--5课本电子版教学内容
以人生为话题的作文-帮家人做家务
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HOW LIFE BEGAN ON THE EARTH
No
one knows exactly how the earth began, as it
happened so long ago.
However, according to a
widely accepted theory, the universe began with a
and combine to create stars and other
bodies.
For several billion years after the
Bangthe earth was still just a
cloud of dust.
What it was to become was uncertain until between
4.5 and
3.8 billion years ago when the dust
settled into a solid globe. The earth
became
so violent that it was not clear whether the shape
would last or not.
It exploded loudly with
fire and rock. They were in time to produce
carbon,
nitrogen, water vapour and other
gases, which were to make the earth's
atmosphere. What is even more important is
that as the earth cooled down,
water began to
appear on its surface.
Water had also
appeared on other planets like Mars but, unlike
the earth,
it had disappeared later. It was
not immediately obvious that water was to be
fundamental to the development of life. What
many scientists believe is that
the continued
presence of water allowed the earth to dissolve
harmful gases
and acids into the oceans and
seas. This produced a chain reaction, which
made it possible for life to develop.
Many millions of years later, the first
extremely small plants began to
appear on the
surface of the water. They multiplied and filled
the oceans and
seas with oxygen, which
encouraged the later development of early
shellfish
and all sorts of fish. Next, green
plants began to grow on land. They were
followed in time by land animals. Some were
insects. Others, called
amphibians, were able
to live on land as well as in the water. Later
when the
plants grew into forests, reptiles
appeared for the first time. They produced
young generally by laying eggs. After that,
some huge animals, called
dinosaurs,
developed. They laid eggs too and existed on the
earth for more
than 140 million years.
However, 65 million years ago the age of the
dinosaurs ended. Why they suddenly disappeared
still remains a mystery. This
disappearance
made possible the rise of mammals on the earth.
These
animals were different from all life
forms in the past, because they gave birth
to
young baby animals and produced milk to feed them.
Finally about 2.6 million years ago some small
clever animals, now with
hands and feet,
appeared and spread all over the earth. Thus they
have, in
their turn, become the most important
animals on the planet. But they are
not
looking after the earth very well. They are
putting too much carbon
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dioxide into the atmosphere, which prevents
heat from escaping from the
earth into space.
As a result of this, many scientists believe the
earth may
become too hot to live on. So
whether life will continue on the earth for
millions of years to come will depend on
whether this problem can be solved.
A VISIT
TO THE MOON
Last month I was lucky enough to
have a chance to make a trip into space
with
my friend Li Yanping, an astronomer. We visited
the moon in our
spaceship!
Before we left,
Li Yanping explained to me that the force of
gravity would
change three times on our
journey and that the first change would be the
most powerful. Then we were off. As the rocket
rose into the air, we were
pushed back into
our seats because we were trying to escape the
pull of the
earth's gravity. It was so hard
that we could not say anything to each other.
Gradually the weight lessened and I was able
to talk to him. is the
spaceship not falling
back to the earth? On the earth if I fall from a
tree I will
fall to the . are too far from the
earth now to feel its
pull,
closer to the
moon, we shall feel its gravity pulling us, but it
will not be as
strong a pull as the earth's.I
cheered up immediately and floated
weightlessly around in our spaceship cabin
watching the earth become
smaller and the moon
larger.
When we got there, I wanted to explore
immediately.
smaller and I will be able to
move more freely. I might even grow taller if I
stay here long enough. I shall certainly weigh
less!I laughed and climbed
down the steps from
the spaceship. But when I tried to step forward, I
found
I was carried twice as far as on the
earth and fell over. cried,
while I got
the hang of it and we began to enjoy ourselves.
Leaving the moon's gravity was not as painful
as leaving the earth's. But
returning to the
earth was very frightening. We watched, amazed as
fire
broke out on the outside of the spaceship
as the earth's gravity increased.
Again we
were pushed hard into our seats as we came back to
land.
was very exhausting but very exciting
too,
about gravity! Do you think we could visit
some stars next time?
he smiled,
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CAUGHT BY A BLACK HOLE
The
spaceship warned Li Yanping and me to be ready as
we were
approaching the holeWe could see some
faint lights around what
looked like an empty
space. Li Yanping said,
always needing to be
fed. Those lights are things that are being pulled
into it
by the gravity of the hole.
lights
which seemed to be going fainter and fainter round
the edge of the
black hole. Just then the
lights on our spaceship went out and the computer
stopped working. What was happening? I tried
to turn the spaceship away
from the hole but
it would not move. Would it eat us too?
Suddenly the spaceship jumped and began to
move round the edge of
the hole too. The
gravity of the
As the spaceship moved round
the black hole, I felt rather sick. My mouth
went dry and I closed my eyes. All the stories
about what happened when
you were caught by
the gravity of a
But then the spaceship jumped
again. This time it moved sideways and
away
from the edge of the
seen the spaceship flying
like a bird away from the
nothing. At last we
were able to look around us. Luckily the computer
had
started working again. We realized that we
had discovered something new
about
you and
there is no escape; but if you do not, you may
have an opportunity
to escape. How
exciting!
Unit5
A TRIP ON
Li Daiyu
and her cousin Liu Qian were on a trip to Canada
to visit their
cousins in Montreal on the
Atlantic coast. Rather than take the aeroplane all
the way, they decided to fly to Vancouver and
then take the train west to east
across
Canada. The thought that they could cross the
whole continent was
exciting.
Their
friend, Danny Lin, was waiting at the airport. He
was going to take
them and their baggage to
catch True Norththe cross-Canada train.
On the
way to the station, he chatted about their trip.
some great scenery. Going eastward, you'll
pass mountains and thousands of
lakes and
forests, as well as wide rivers and large cities.
Some people have
the idea that you can cross
Canada in less than five days, but they forget the
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fact that Canada is
5,500 kilometres from coast to coast. Here in
Vancouver,
you're in Canada's warmest part.
People say it is Canada's most beautiful city
surrounded by mountains and the Pacific Ocean.
Skiing in the Rocky
Mountains and sailing in
the harbour make Vancouver one of Canada's most
popular cities to live in. Its population is
increasing rapidly. The coast north of
Vancouver has some of the oldest and most
beautiful forests in the world. It
is so wet
there that the trees are extremely tall, some
measuring over 90
metres.
That afternoon
aboard the train, the cousins settled down in
their seats.
Earlier that day, when they
crossed the Rocky Mountains, they managed to
catch sight of some mountain goats and even a
grizzly bear and an eagle.
Their next stop was
Calgary, which is famous for the Calgary Stampede.
Cowboys from all over the world come to
compete in the Stampede. Many of
them have a
gift for riding wild horses and can win thousands
of dollars in
prizes.
After two days'
travel, the girls began to realize that Canada is
quite
empty. At school, they had learned that
most Canadians live within a few
hundred
kilometres of the USA border, and Canada's
population is only
slightly over thirty
million, but now they were amazed to see such an
empty
country. They went through a wheat-
growing province and saw farms that
covered
thousands of acres. After dinner, they were back
in an urban area,
the busy port city of
Thunder Bay at the top of the Great Lakes. The
girls
were surprised at the fact that ocean
ships can sail up the Great Lakes.
Because of
the Great Lakes, they learned, Canada has more
fresh water than
any other country in the
world. In fact, it has one-third of the world's
total
fresh water, and much of it is in the
Great Lakes.
That night as they slept, the
train rushed across the top of Lake Superior,
through the great forests and southward
towards Toronto.
“THE TURE NORTH” FROM
TORONTO TO MONTREAL
The next morning the
bushes and maple trees outside their windows were
red,
gold and orange, and there was frost on
the ground, confirming that fall had
arrived
in Canada.
Around noon they arrived in
Toronto, the biggest and most wealthy city
in
Canada. They were not leaving for Montreal until
later, so they went on a
tour of the city.
They went up the tall CN Tower and looked across
the lake.
In the distance, they could see the
misty cloud that rose from the great
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Niagara Falls, which is on the
south side of the lake. The water flows into the
Niagara River and over the falls on its way to
the sea.
They saw the covered stadium, home of
several famous basketball teams.
As they
walked north from the harbour area, Li Daiyu said,
my mother's old schoolmates, lives here. I
should phone her from a telephone
booth.
They met Lin Fei around dusk in
downtown Chinatown, one of the three
in
Toronto. Over dinner at a restaurant called The
Pink Pearl, the cousins
chatted with Lin Fei,
who had moved to Canada many years earlier.
get good Cantonese food here,Lin Fei told
them, most of the
Chinese people here come
from South China, especially Hong Kong. It's too
bad you can't go as far as Ottawa, Canada's
capital. It's approximately four
hundred
kilometres northeast of Toronto, so it would take
too long.
The train left late that night and
arrived in Montreal at dawn the next
morning.
At the station, people everywhere were speaking
French. There
were signs and ads in French,
but some of them had English words in smaller
letters.
Old Montreal is close to the
water.
and visiting artists in their workplaces
beside the water. As they sat in a
buffet
restaurant looking over the broad St Lawrence
River, a young man sat
down with them.
train trip across Canada and that they
had only one day in Montreal.
too bad,he said.
is a city with wonderful restaurants and clubs.
Most of us speak both English and French, but
the city has French culture and
traditions. We
love good coffee, good bread and good
music.
That night as the train was speeding
along the St Lawrence River toward
the Gulf of
St Lawrence and down to the distant east coast,
the cousins
dreamed of French restaurants and
red maple leaves.
IQALUIT-- THE FROZEN TOWN
The reporter, Beth Allen, arrived in a
northern community called Iqaluit in
Nunavut
.Nunavut was created in 1999 as a special area for
Inuit people. Its
name means
area of
Canada, north of the Arctic Circle, and is very
cold - the average
winter temperature in
Nunavut is 35 degrees below zero.
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Beth said,
there is a dog
sled that can take me into town.
The quiet man
who had been on the plane with her said,
into
town, but I don't have a dog sled. Most people
only use the dogs for
competitions. Why are
you visiting Iqaluit?
Beth answered, writing a
story for my newspaper about Iqaluit -
we'd
like to advertise it as a holiday place, but I
think it's too cold.
The man laughed.
it's
too far north here for holidays but more and more
tourists are coming.
They like ice fishing and
photographing polar bears. I stay as far away from
polar bears as possible. I like my warm office
and my warm house.
Beth asked,
living? I
thought you lived in ice houses.
business man.
My grandfather would live in ice houses when he
hunted in winter, but not so many people do
that now. The old men used to
make one in a
few hours. They used to live in skin tents in
summer - the
tents were easy to move so the
people could follow the animals.
A few minutes
later they arrived in Iqaluit, a town with a
population of
6,000, on Simon's snowmobile. It
was two o'clock in the afternoon, but it was
already dark, and all the houses shone with
bright lights. Beth said,
so dark? It's the
middle of the day!
Simon replied, dark in the
day because we are so far north. You
should
come in June. The sun shines all night in the
north then. That's why
it's called 'The Land
of the Midnight Sun'.
and snowmobiles
everywhere. There were even a few dog teams.
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