Today many people are cutting down the trees in the forests. A lot of rich land has become   (1)    .If we read newspapers, we’ll learn that the forests on the earth are getting   (2)  all the time. We are cutting down lots of trees because we need  (3)   . Some scientists say that there will be not any great forest   (4)     20 or 30 years.

      What will happen if the forests disappear? A lot of plants will die    (5)   the animals will lose their home. In many places new farmland will soon look like olddersert.Cropswill not  (6)    there .There won’t be enoughrain,andthe weather get hot and   (7)    .If the climate of the earth changes, our living environment will   (8)    become worse andworse.Moreand more rich farmland will  (9)   .We will suffer (遭受) a lot from both droughts and floods.

  It’s our duty to protect the forests well.   (10)  

Editor Henry Slocum，I read your May 10th article in the local newspaper aboute-books，with great inerest．You made several good points about the____  (1)  ____0f e-books.Yes，e-books are expensive but they are also convenient and____  (2)  ____for our nature．E-books are about the same____  (3)  ____and shape as regular books．They have a large____  (4)  ____in the middle．This screen____  (5)  ____the reader a

page of text that has been downloaded from acomputer．Once the reader____  (6)  ____reading one page on the e-book screen,he or she

scrolls(滑动)down to see a new page．As you pointed out，it’s great to lie on a warm，sandy beach with a book.You can do that____  (7)  ____，because e-books are so light，you carry them any where.For example，you like to read on the bus．Which would you like to____  (8)  ____with you—a heavy 800—page novel，or an e-book that weighs only a few ounces?At present，thousands of trees are cut down each year____  (9)  ____the paper factory．Books that don’t sell are returned to the____  (10)  ____ and desgoyed．This tcrrible waste could be avoided if everyone used e-books．

Sincerely，

David

As we know, life today has many problems. One of the biggest is____36_____, such as water pollution, air pollution, __37__ pollution and so on. Water pollution makes our rivers and lakes __38__. It kills our fish and pollutes our drinking water. Air pollution is the most serious(严重的) kind of pollution. __39__bad for living things in the world. Noise pollution ___40__ us talk louder and makes us become angry___41___．The Earth is__42___ home and we must save it. We canˈt __43__ waste here and there. We should go to work and school by bus___44__ with our friends in the same car. Everybody__45_  save the Earth.

When people think of tigers, they think: strong and dangerous. But now, the big animal is calling for our help.

There were once eight kinds of 16 ______in the world, but three died out during the 20th century. In the last 70 years, the 17       _____   of Siberian tigers (东北虎) has gone from as many as 300 to 18 _____22 somewhere. The Siberian tiger has been1 9  ______ dying out completely.        If the government doesn't make any efforts, it's quite 20  ______that there  will be no more Siberian tigers in China in ten to twenty years.

In order to double the number of wild tigers in the21 _____ ten years, the World Wildlife Fund (世界自然基金会) has started a program recently. It aimed to（目的在于）save wild tigers and put an end to tiger hunting and 22 ____.China, together with twelve other 23 ______, has joined in.

Wild animals, such as red deer and wild pigs, are the main 24 ______of the tigers. The hunting of these animals is the greatest threat(危险) to tigers. So the most important thing is25 ______the animals that tigers eat. To protect the wild tigers, we need to call on more people to stop eating and hunting wild animals.

Flies (苍蝇) usually live in the dirty places.

Let’s look at a fly, and see where it   (1)  . First, it flies out of the window,   (2)   it stands on   (3)   dirty things in the street, and then it flies back to the house and walks over your   (4)  .

When a fly walks on the dirty things in the street, its   (5)   have got some germs   (6)   them. When the fly walks on your food with its dirty feet, it   (7)   the germs on your food.

What can you   (8)   this?

First, we learn that we mustn’t leave dirty things in the street or on the ground near   (9)  . Second, we learn that all food must be covered so that flies may not   (10)   it. Third, we learn that flies often carry germs and we must kill them as soon as we see them.

Many places in the world need more fresh water. Every country is trying to find ways to turn salt water  (1)  fresh.

    Why  (2)  there many factories like the Symi factory?

    In some places, the sun is not  (3)  . Or it does not shine every day. In such places,  (4)  ways of heating sea water can be used. These ways cost    (5)  money, but they work faster than the sun.   (6)  boiling sea water with high heat, a lot of fresh water can be made quickly.

    But  (7)  is not the only way to get fresh water from salt water. Other ways are tried.

     One way is freezing(冷冻). The fresh part of salt water freezes first. To get fresh water, the pieces of ice are taken out.

    Which way is  (8)  ? The one that gives the most water for the least money. It   (9)   a different way for each place.

    Symi's way seems very good for small, hot places. It does not make very much water at a time. But the factory is easy to be built and   (10)  little.

    That is why people in many dry places talk about Symi!

A city withoutcars would be very strange, right? But Venice(威尼斯) is such a city.

Venice is in thenortheast of ________(21)_. It wasn’t built on land, like Beijing or Shanghai, but on more than 110 islands. Seawater is everywhere _________(22)_ the city.

Even so, travel isn’t so difficult. The waterways have always been the best way to get around. There are 117 waterways and more than 400 __________(23) that can lead you where you want to go.

People in Venice move from place to place by __________(24)_. They like to enjoy cool summer nights while taking boat trips. They can _______(25)_ other people as they go along.

Venice grew out ofsmall islands in saltwater lakes when some Italians escaped（逃脱) from a war more than 1,500 years ago and built homes there._________(26) makes the city special, but it is also a big problem.

Once people used too much underground water. This made the city get _______(27)_ little by little. Now the city has gone down by 23 centimetres. Every year, high water hit the city in autumn and winter. When _________(28) water comes, more than half of the city is under water.

Another problemis the rising seawater. The _________(29)_ has risen over the years. This has made Arctic(北极的)ice melt（融化）．Scientists aretrying different ways to stop the city from getting even __________(30).

The universe(宇宙) is really mystical（神秘的）. Scientists have done lots of study about it but there is still much they haven’t   (1)   .

Scientists think that people   (2)   on the earth for many many years. However , we haven’t found life on any other planet yet .

There are eight planets going   (3)   the sun . The earth is one of them . There are humans , animals , plants and many other kinds of life on the earth . There is water and air , too . And compared to the other planets , the earth is not too hot or too cold .   (4)   of seven other planets has an environment like that of the earth . So the earth is our only home.

The sun and its planets are called the solar system（太阳系）, and our solar system is a small part of a much larger group of stars and planets , called the Galaxy（银河）or the Milky Way（银河系）. There are over 200 billion   (5)   in the Galaxy, and our sun is only one of them.

There are many other galaxies in the universe as well. Their light has to travel for many years to reach us. So   (6)   is the universe? It is impossible to imagine.

Scientists have sent spaceships（宇宙飞船）to the planet Mars to take photos . They have even sent spaceships to travel outside the solar system .   (7)   them , now we have a better understanding of many planets around us . However, no spaceship has traveled   (8)   to reach other stars in our Galaxy.

When we see stars twinkling（闪耀）in the sky   (9)   , we may think a lot : with so many stars in the universe , is there life out there in space ? If there is life on other planets, what life will be like there? What transports(交通工具) do they use to travel ? Why don’t they  (10)   us ? The universe is still a huge mystery.

As we all know, the earth is our home. Everyone should do something to protect the earth. Then, what can we do to help save our earth? Let me tell you something about what my family do.

First, my family try to save     (1)    We never leave the lights on when leaving the rooms. We turn off the TV when     (2)     is watching it. Mom only uses cold water for the washing machine.

Second, we also pay attention to recycling. We     (3)     to write on both sides of the paper, not just on one side. We also     (4)     our rubbish into different bags for bottles, cans, paper and food. Mom keeps the plastic shopping bags from the supermarket to use them again as rubbish bags. These are great     (5)     to help protect our environment.

Third, my family also save water. We never take long baths and have short showers     (6)     We wash the toilet with used water. My sister and I don’t     (7)     the tap （水龙头） running when we brush our teeth.

At last, mom and dad decide to save gas from now on. Mom     (8)     to drive us to school, but now my sister and I start riding our bikes to school. It’s hard work     (9)     good exercise! This week dad and his workmates also start to go to work together in one     (10)     and share the cost. This also help reduce greenhouse gases.

I think these are great ways to help save our earth. Let’s take action right now together!

I can’t remember when I started collecting litter. But it was when I got tired of   26 litter nearby that I realized no one else was going to pick it up.

I live near a forest inOhio, America. I can walk there 27 three minutes. I used to love going there to play with my dog. But one day there was 28 much litter there that I became very unhappy. I decided to clean up the forest, and I wanted to 29 happy when I went there again. I made my first trip to clean the forest that afternoon. I took a big black rubbish bag with me. Ten minutes   30 I started to pick up litter, my bag was full! There were cans, bottles, broken glass and newspapers in it.

From then on, I 31 to the forest four times a year to pick up litter. I often stay there for three hours. It makes me feel 32 to do something for the environment. After each trip, I look through all the litter that I’ve collected. If 33 of it is recyclable (可回收利用的), I’ll keep it. I can’t understand why people drop litter. But I will keep on picking it up 34 they stop dropping it. I know I am only doing a small bit 35 the earth, but I still think it is important.