There is a lot of salt on the Earth, and it mixes very well with water.

There is some salt in all water. Water on the land runs into lakes and rivers. These rivers run into the seas and oceans. They carry a little salt with them. Some of the ocean water moves into the air and clouds. It evaporates. Salt cannot evaporate. It stays in the oceans.

    The water in the oceans has more salt than river water. There is about 3. 5% salt in the ocean water. Some seas have more salt than others.

    Some of the water leaves the lakes. It evaporates, but the salt cannot. These lakes are very salty. There are two famous lakes like this. They are the Dead Sea in the Middle East and the Great Salt Lake in Utah(犹他州）in the United States. They are much saltier than the Atlantic Ocean（大西洋）and the Pacific Ocean(太平洋）.

    Sometimes people call each other “scared-cat”, but have you ever thought about this expression? When a cat is frightened, its heart starts beating faster, its muscles get tense (紧张的), and there are changes in the chemicals in its bloodstream. Although the cat doesn't realize this, its body is getting ready for action. If the danger continues, the animal will do one of two things. It will protect itself, or it will run away as fast as it can.

    Something like this also happens to people. When we are excited, angry or scared by other feelings, our bodies go through many physical changes. Our hearts beat faster, and our muscles get tense. All of these changes make us more alert and ready to react. We, too, get ready to defend ourselves or run.

   Human beings, however, have a problem that animals never face. If we give way to our feelings and let them take over, we can get into trouble. Have you ever said something in anger — or hit somebody — and regretted it later? Have you ever shouted at a teacher, told somebody you were lonely, or said you were in love, and then wished later you had kept your mouth shut? It isn't always clever to express your feelings freely.

    Does this mean that it's smarter always to hide (藏) our feelings? No! If you keep feelings of anger, sadness hidden away or bottled up inside, your body stays tense. Physical illness can develop. It can actually be bad for your health. (It isn't good to keep pleasant feelings inside either; all feelings need to be expressed.)

    Feelings that you keep all bottled up inside don't just go away. It's as if you bought some bananas and stuck them in a cupboard. You might not be able to see them, but before long you'd smell them. And if you opened the cupboard, chances are you'd see little fruit flies flying all over them. They'd be rotten (腐烂).

    You can try to treat feelings as if they were bananas in the cupboard. You can hide them and you can pretend they don't exist, but they'll still be around. And at last you'll have to deal with them, just like those bananas.

    Populations of white-tailed deer(白尾鹿) are growing rapidly in many parts of the United States. As populations grow, food becomes a problem. Many deer die of hunger. Others grow up small and unhealthy. In search of food, hungry deer move closer to where humans live. They eat farm crops, vegetables and even trees. Besides, increased numbers of deer near roads can cause traffic accidents.

    People admire the grace and fast speed of deer. Most people don't want these animals to be hungry and ill. Should people take action to control the growing deer populations?

Should People Take Direct Action?

    Many people think that hunting(打猎) is the best way to control the animal populations. Wildlife managers will see if there's enough food in an area and decide its carrying capacity(容量). Then hunters with licenses are sent to help control the number of deer. Hunting is usually not allowed in cities or suburbs, however.

    Some people have the idea to catch the deer and move them to other places. But this method is expensive and requires finding another place that can accept the deer without breaking the balance of ecosystem(生态系统).

    Scientists are also working to develop chemicals(化学药品) to control the birth rate(率) in deer populations. But this plan works for only one year at a time.

Should People Take Indirect Action?

    Some suggest bringing in natural enemies of deer, such as wolves, lions and bears, to areas with too many deer. But these animals could also hurt dogs, cats, and even humans. Other communities have built tall fences(篱笆) around areas to keep out the deer. However, this is impossible for farmers.

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    Some people are against any kind of action. They support leaving the deer alone. Animal populations in an area naturally go up and down over time. Doing nothing means that some deer will die of hunger or illness. But finally, the population will reach a size within the carrying capacity(容量) of the environment. So, let nature go its own way.

    This is a street crossing. There are red and green lights at each corner. Drivers must watch the lights carefully.

    When there is a green light, the cars may go on. When there is a red light, the cars must stop.

    They must wait until the red light changes (变成)to green. Then they can go on. Sometimes the cars want to make a right turn or a left turn. They can make a right turn when the light is green or red. But they must wait until the green light is shining (闪亮) if they want to turn left. Some people are color-blind (色盲的). They can't see the difference (不同点) between red and green. These people mustn't drive, or there may be an accident (事故) .We must keep our street safe (安全的).

    We have to be fit, no matter (不管) what age we are. It's very important for kids. That's w{#blank#}1{#/blank#} they have P.E. class.

    In Britain students have two hours of P.E. each week. P.E. includes sit-ups, press-ups (俯卧撑) and skipping rope.

    Students also p{#blank#}2{#/blank#}football, basketball and cross-country running. In summer kids run and do the high and long jumps.

    When I was at school my favourite was trampoline(蹦床). Jumping high into the air always made me excited. But you need to be c{#blank#}3{#/blank#}. Sometimes you don't land where you planned!

    When you get your report card there will be a grade for P.E.. Your parents will see how good you are a{#blank#}4{#/blank#} push-ups, as well as maths. But the grade for P.E. doesn't affect (影响) your chances of g{#blank#}5{#/blank#} into a good school.

    When people think of tigers, words like" strong" and " dangerous" come into their mind. But now, the big animal is calling for our help. There were once eight kinds of tigers in the world, but three died out during last century. In the past 70 years, the number of Siberian tigers has gone from as many as 300 to somewhere between 18 and 22.

   World Wildlife Fund started a programme. It is about to put an end to tiger poaching(非法狩猎) and save wild tigers. China, together with 12 other countries, has joined in. The aim is to double the number of wild tigers in the next ten years.

According to the research by Chinese officers and WWF, the Siberian tiger is already one of the planet's most endangered animals. "If the government doesn't do anything, it's quite possible that there will be no more Siberian tigers in China in 10 to 20 years." said Zhu Chunquan, director at WWF Beijing office.

    Wild animals such as deer and wild bears are tigers' main food. The poaching of these animals is the greatest danger to tigers. Another one is the trap(陷阱). "Volunteers from WWF remove traps every year, but we cannot clear all the traps ourselves," Zhu said. The most important thing people can do is to save the animals tigers eat." To protect the tigers, we need to call on more people to stop hunting wild animals."