Deserts are found where there is little rainfall or where rain for a whole year falls in only a few weeks' time. Ten inches of rain may be enough for many plants to survive (存活) if the rain is spread throughout the year, If it falls within one or two months and the rest of the year is dry, those plants may die and a desert may form.

    Sand begins as tiny pieces of rock that get smaller and smaller as wind and weather wear them down. Sand dunes (沙丘) are formed as winds move the sand across the desert. Bit by bit, the dunes grow over the years, always moving with the winds and changing the shape. Most of them are only a few feet tall, but they can grow to be several hundred feet high.

    There is, however, much more to a desert than sand. In the deserts of the southwestern United States, cliffs (悬崖) and deep valleys were formed from thick mud that once lay beneath (在……之下) a sea more than millions of years ago. Over the centuries, the water dried up. Wind, sand, rain, heat and cold all wore away at the remaining rocks. The faces of the desert mountains are always changing--very, very slowly--as these forces of nature continue to work on the rock.

    Most deserts have a surprising variety of life. There are plants, animals and insects that have adapted (适应) to life in the desert. During the heat of the day a visitor may see very few signs of living things, but as the air begins to cool in the evening, the desert comes to life. As the sun begins to rise again in the sky, the desert once again becomes quiet and lonely.

    There are some skills for students to listen to the teachers in class, which means you're going to have to practice them. Just as you would have to practice basketball to be a better player, you also have to practice listening. How to listen in school? {#blank#}1{#/blank#}

    One of the things you'll need to do is to make sure that your mind doesn't wander(漫游). It's easy to start thinking about other things, especially when you are not interested in the subject. {#blank#}2{#/blank#}

   Next, listen for the main ideas. If you want to catch every little piece of information, you'll feel tired and bored. {#blank#}3{#/blank#} Not only does this show respect to the teacher, it also helps prevent your mind from wandering. {#blank#}4{#/blank#}Or it could just be someone talking to their neighbors who shouldn't be, it can even be some birds outside the classroom window, or a group of kids who are talking loudly as they pass the door to your room.

    Finally, you need to take notes because you will not remember everything the teacher said. You'll have to take down the notes so that you can study it after class. {#blank#}5{#/blank#}

    Listening isn't always easy, but if you follow these simple steps, you'll be much more successful in your classes.

There are many colors in nature. But do you think that a color has weight? Let's do a test.

First, put two objects with the {#blank#}1{#/blank#} weight into two boxes. Then cover the boxes. Third, wrap (包裹) one box with a red piece of paper, the other with white. Now hold the boxes {#blank#}2{#/blank#} your hand one by one. Which one is {#blank#}3{#/blank#} ? It is certain that you will think the red one is heavier. Why do you think so? A scientist did many {#blank#}4{#/blank#} and found that different colors have different weights in a man's mind.

Also, scientists say that people accept the colors they like, and {#blank#}5{#/blank#} the colors they hate. So your body and mind will be {#blank#}6{#/blank#} by using the colors you like. Or you'll be nervous {#blank#}7{#/blank#} even get ill. For example, you {#blank#}8{#/blank#} blue and hate red. If you stay in a room with red windows and wallpaper for two hours, you'll feel you have been there for {#blank#}9{#/blank#} hours. But if the room is blue, you'll feel you have been there for only an hour, And, if a person walks {#blank#}10{#/blank#} of a blue room and into a red room, his temperature will rise. That means our body temperature will change with different colors.

What would you do if you see someone hurt badly? The following will help you to learn some important skills to give casualty (伤员) first aid.

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The first and most important thing you must do is to make sure the place is not dangerous. Can you see anything that might not be helpful to you? Can you hear anything that could be dangerous?

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When you see someone has been hurt, you may feel scared. If you feel yourself starting to be nervous, try to calm yourself down. For example, talk to people you trust about what happened, and you'll be relaxed.

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When someone needs first aid, talking to him will help him to stay calm and feel safe. Even if he does not answer you, you should still tell him what you are doing. It will let him know that you are helping him.

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Sometimes, the casualty will need more help than you are able to give. The best thing you can do is to phone some people for help. They can give you some useful advice or offer you some help.

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There are also many other things to do. Try your best to help the casualty. Asking people around you for help is really better than waiting for doctors. Besides, you can also try to keep in touch with his families and friends.

Until the beginning of July, there has been no rain in northern Italy for over 100 days. Add to that the high temperatures, and the locals get very dry conditions. This is the most serious dry spell（干旱期）for that area in the past 70 years. Because of this situation, the country's longest river, the Po, is drying up!

This is bad news for several different reasons. The fresh water of the Po provides drinking water for northern Italy. Besides, farmers in this area need the water of the Po to keep their crops growing. What's more, the flowing river water is used to create about half of the hydroelectric power（水力发电）for Italy. Its drying up means that more natural gas（天然气） will be used, which is bad for the environment.

There have been some interesting discoveries from this lack of rain, however. Between Florence and Milan, a long ship sunk （沉没）in 1943 appeared because of the low water levels of the river. Now many tourists and locals come to see this ship. A German tank has also appeared out of water near Mantua. At other places along the river, people can even walk on the sandy river bed. Although this may be interesting, people in Italy and around the world are hoping for the return of rain to refill the Po!

Laura has {#blank#}1{#/blank#} problems. She doesn't know whether she is going to {#blank#}2{#/blank#} or {#blank#}3{#/blank#} Also she can't decide how to get to the party, by {#blank#}4{#/blank#} or by{#blank#}5{#/blank#}.