英语八下课文

Judy is collecting some facts for a class project on pollution .She is interviewing Doctor Ray, a scientist , about trees.

JUDY: Why are you so interested in trees, Doctor Ray?

DR RAY: They‘re the biggest and oldest living things on

the earth , Judy.

JUDY: Yes ,

but what good are trees ? They make streets more beautiful and less noisy , but what else can they do ?

DR RAY: Well , the wood in your pencil ,the rubber on the end of your pencil ,the paper in your notebook and the fruit in your bowl all come from

trees . And I suppose you also enjoy breathing pure, cool air.

JUDY: Of course.

DR RAY: Then you must thank trees for that

too . They take harmful gases from the air ,and release oxygen into the air . How many people are

there in your class , Judy ?

JUDY: Forty-six .

DR RAY: Well , one and a half hectares of trees could produce enough oxygen to keep your whole class alive and healthy for a

whole year . JUDY:

That's wonderful!

DR RAY: Trees cool the air as well as clean it .They are natural air trees can do the job of 15 air conditioners running almost all

day .

JUDY: You certainly know a lot about trees ,Doctor Ray .

DR RAY: Thank you ,Judy ,but I don't ,really . Scientists are only now beginning to understand them . For example , when insects attack a tree , it

can warn its neighbours ? The trees can then protect themselves by producing a chemical that makes their leaves taste nasty . And some trees can join

their roots together underground ,and pass food and water to each other . Trees are communicating with one another , but we don't know how .

JUDY: Are trees in danger ?

DR RAY: In great danger . We cut down and burn millions every year but we replace hardly any of them .We are destroying our best fighters against

pollution.

Almost everyone today uses electricity in one way or another. It is hard to imagine what life in our cities would be like without it. Electricity lights

streets and buildings, and warms people and animals. It heats food in cookers and cools it in refrigerators. It drives trains and works traffic lights and

lifts. It also works the machines in factories that make all kinds of goods. Everyday wonders such as computers and televisions use electricity to bring

entertainment and news to millions of families. In villages and on farms, electrical

machines

milk the cows and chop their food. They also cool the

milk and churn the butter. Indeed, electricity find as much as work to do in the countryside as it does in the cities.

Daisy was in the bathroom. She was brushing her teeth and the tap was on.

Water was pouring into the washbasin and vanishing down the drain.

impatient.

This time Daisy obeyed. 'Who ... who are you? 'Daisy's voice was faint.

'I'm a drop of water. It's not easy for me to get here. Do you know where I'm from?'

'From the tap, I suppose, 'said Daisy.

'Yes, but before that?' the voice said.'A few days days ago,I was floating comfortably in a cloud in Jiangxi, enjoying the view. Then the cloud dropped

me into a stream and I sped down the mountain into the Yangtze River. the Yangtze River carried me to a lake. I relaxed there for a few days, and

then I travelled a long way and ran into the Huangpu River. Then it was time to get cleaned up.'

'Cleaned up?'Daisy sounded puzzled.

'Yes. I was dirty after my journey so they took me to a water treatment works.

They gave me a thorough cleaning and added a few chemicals to me. Then I travelled in the pipes under the streets. I waited there until you called

me,and here I am.'

Daisy said, 'So this is the end of your journey.'

' you've finished with me,I'll go to a sewage plant. Then they'll pump me into the riverand I'll be back in the sea again.'

'Again?'

's where I came from in the first place. Remember not to waste me or pollute me. I'm precious,like liquid you.'

'Wait

a

do

you

mean

by

liquid

gold?'But

there

was

no

reply.

The

water

had

gone.

Daisy

came

out

of

the

bathroom.

Her

brother

said,'Who were you talking to?' 'To the water,'Daisy said.

Sometimes you're strange, Daisy,'her brother said.

Dear friends:

Trees are our friends. They work hard for us. They cool our cities and clean the air .They also give out oxygen for us to breathe. Trees reduce sound

pollution in cities and make cities more beautiful. Without trees, the soil would be washed away and there would be no food for us to eat. Without

trees, it would get too hot for us to live on earth. Without trees, we would die.

Trees also provide a lot of things for people. They provide food. They also supply material for houses ,furniture and paper products. Some trees even

provide important ingredients for medicine.

In the last 200 years, more than half of all the trees on earth have been destroyed. We need more trees!

Trees for Life is making a difference. To help protect our environment, we plant trees and take care of them. we need more people to join us in this

project.

We

want

to

plant

100

million

trees

in

the

next

10

years.

If

you

want

to

find

out

more

about

us,

please

send

us

an

e-mail

at

info@.

From

Trees for Life

The oceans cover 2/3 of the Earth, but ocean water is salty. That is to say, most of the water on the Earth is not drinkable!

90% of all the water on the Earth that human beings can drink right now is underground. It is very easy to pollute groundwater. For example, 4.5

litres of paint or about 1 litre of motor oil can seep into the Earth and pollute 1,125,000 litres of drinking water!

A leak that fills up a coffee cup in 10 minutes will waste over 13,500 litres of water in a year. How much water is that? You would have to drink 65

glasses of water every day for a year to get that much water!

If you leave the water running while you brush your teeth, you might waste 22.5 litres of water. That is enough to fill 65 cans of soft drink!

If you leave the water running while you wash the dishes, you might waste 135 litres of water

—

enough to wash a whole car!

Believe it or not, the water we flush down our toilets starts as fresh water! Each time you flush, your toilet uses about 9 to 15 litres of water. But it does

not have to!

A shower usually takes at least 5 minutes. So every day, you could use 112.5 litres of water taking one shower. In a year, that is almost 45,000 litres of

water!

A bath uses even more water than a shower

—

about twice as much. A bath can easily use 225 litres of water

One evening, Daisy said, 'I'm going to buy a packet of sweets. Does anyone want anything?'

Benny, Daisy's brother, said, 'Yes. Can you get me a packet of electricity, please?'

Daisy said, 'OK' and went out. Benny laughed. 'Ha! Ha! I've tricked Daisy at last. She doesn't even know what electricity is. She thinks that she can

buy it in packets, like sweets! She'll really look foolish.'

Mum said, 'Do you know what electricity is?'

Benny said, 'Yes. Electricity flows through a wire. A meter measures the amount you use, and you get a bill for it monthly. It's like water, in a way.'

'That's not a bad explanation,' said Dad, 'Although electricity is much more dangerous than water. Electricity is a good servant, but a dangerous one.

You must always be careful with it. Can you tell what it looks like?'

Benny scratched his head.

Dad said, 'Nobody's even seen electricity. It's invisible. But we can change it into different forms of energy that we can see, heat or feel. Can you think

of an example?'

Benny said, 'Light! The light in a light bulb.'

Mum said, 'That's right. Do you know where electricity comes from?'

Benny said, 'Well, it comes into our flat through thin wires, and these are connected to thick wires that are buried under the street.'

'We call the thick wires cables,' said Dad. 'What are they connected to?'

'A power station.' said Benny.

Daisy then came back. Benny asked politely, 'May I have my packet of electricity, please?' There was a grin on his face.

'Yes, you may,' said Daisy. 'Here it is.'

Benny said, 'But these are batteries!'

Daisy said, 'That's right.'

'But...but...'said Benny.

'Daisy's right,' said Dad. 'They're packets that contain electricity. The chemicals inside produce electricity.'

Daisy asked, 'Didn't you know that, Benny?'

Mum said, 'Who's looking foolish now, Benny?'

Benjamin

Franklin

was

born

in

Boston,

Massachusetts

in

the

USA

on

17

January

1706.

He

had

a

very

big

family---his

parents

had

seventeen

children .He was a man of many talents and interests .Among other things ,he was a scientist and inventor .He was naturally curious about the way

things worked and was always searching for ways to make them work better.

In 1747,Benjamin began his experiments

on electricity

with some very simple equipment. Although these experiments led to the

discovery of some

very important findings on electricity, Benjamin did not actually invent it. However, he did invent the lightning conductor ,which protects buildings

and ships from damage caused by lightning.

Benjamin had poor vision and needed glasses .He was tired of always taking them on and off ,so he decided to invent a pair of glasses that would let

him see both near and far things at the same time .He took the two different types of glasses, cut each lens in half, and then put half of each lens into

another frame. Nowadays, this type of glasses is known as bifocals.

During his lifetime, he travelled across the Atlantic Ocean eight times. These long journeys gave him a lot of time to learn about how ships worked. He

developed

a

way

to

make

them

safer

and

more

efficient

by

inventing

watertight

bulkheads.

Other

developments

in

safety

that

he

made

included

establishing the first fire company in Philadelphia, USA, and improving the city

‘

s street paving and lighting of the city

‘

s streets.

John

Dancer‘s troubles began as soon as he walked into the Dragon Hotel with his friend, Charlie. Together they went to the

reception desk. John said,

―My name‘s Dancer. I‘ve booked a room here. The clerk said, ―You‘re welcome to stay, sir, but we don‘t allow pets in this hotel.‖

―Pets

!‖

exclaimed

John. ―Charlie isn‘t a pet. I‘m blind and he‘s my eyes.

He takes me

everywhere. Don‘t you, Charlie?‖ Charlie barked. It sounded

like

―Yes‖.

―I‘m sorry, sir, ―the clerk repeated, ―but the hotel rules say …‖ John interrupted, ―:Please call the manager.‖

The manager came. He agreed at once that John and Charlie could both be guests. He led them to their room. Before entering

, John said, ―

Can you

tell me the location of the first exit

?‖

―It‘s the fifth door along from yours,‖ said the manager.

―Thank you,‖ said John. ―Safety first, you know.‖

―You‘re very

sensible

, sir,‖ the manager said. He then described John‘s room to him, and left. John tells us in his own words

what happened next.

―I was

asleep. Charlie woke me. He was pulling at my blankets and barking. I smelt smoke! A fire! But where? Just then, the fire alarm went off. I

went to the door of my room. I felt it. The surface

was hot so I didn‘t open it. The fire must

be outside. I wet some towels

and put them along the

bottom of the door.

―I tried the phone. It was

dead. I coughed. A little smoke was getting past the towels. So I lay on the floor with Charlie beside me and waited. The

minutes seemed like hours. Then I heard it

–

the sound of a fire engine. It was music to my ears.

―I opened the window, waved and shouted. Charlie barked. Moments later, I heard a voice. The fireman at the window didn‘t wan

t to take Charlie.

―

It

‘

s against the rules

,‖ he said. I explained about Charlie. Seconds later, we were both safe on the ground.‖

―So you saved Charlie‘s life!‖ I said.

―Yes, and he saved mine,‖ said John. ―Didn‘t you, Charlie?‖

Charlie barked. It sounded like ―Yes‖.

The tower of Pisa was built to be the most beautiful bell tower in all of is the bell tower for Pisa Cathedral. However,not only is the marble

tower beautiful,it is perhaps the strangest tower in the leans to one side and looks like it is going to fall over.

The

building of the tower began in August 1173 and took nearly tow hundred years to is certain who designed the tower,but

for

many

years

it

said

that

Bonanno

Piisano

was

the

architect,ln

1319,all

the

floors

were

finished

and

years

laters,work

eventuallybegan

on

the

bell

chamber at the wasofficially opened after nearly 200 years of tower has eight is 54.5 metrestall with 294 steps up to the

bell the

top,there

is a very

beautiful n scientist,Galileo ,once

did

his famous experiments

about

gravity and

falling objects

from the top of the tower.

Why does the towerlean?ln fact,it was already while they are building soon as three floors had been built,bu 1178,it began to lean as the ground

beneath it builders tried to make the tower straight again as they adde more floors,but the lean only go worse as the tower cotined to

lean by about 1 millimetre every year until finally,on 7 January 1990,it was closed to the public,For ten pears,the rescue of the tower was a serious

top was leaning

over by 5metres

to the

south and if its movement

was

not

stopped,the

tower

would one

day fall

over.

Measurements

taken

in

1911

showed

that

the

tower

would

collapse

by

2050,if

not

10

years

of

hard

work,it

was

officially

reopened

on16

June

r,it

was

not

opened

to

the

public

until

the

end

of

2001

and

even

now,the

number

of

visitors

is

is

now

safe

for

the

next

300years because engineers have reduced the lean by 50 centimetres to give it the same lean that it had in 1838.