When the weather is hot, you go to a lake or an ocean. When you are near a lake or an Ocean, you feel cool. Why? The sun makes the earth hot, but it cannot make the water very hot. Although the air over the earth becomes hot, the air over the water is still cool. The hot air over the earth goes up. Then the cool air over the water moves in and takes the place of the hot air.

    Then you may ask, "Why is the ocean full of salt?" Scientists will say that the salt comes from the rocks. When the rocks get very hot or very cold, they crack (爆裂). Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. And then you may doubt, "But the ocean does not get more salty every year. Scientists are not sure about the answer to this question.

    We know a lot about our world. But there are still many answers that we do not have, and we are curious about them.

    Imagine you are taking a walk on the beautiful beach. Just then, your feet step over something and you hear a crack (噼啪声) —an empty plastic bottle. Things like this are happening more often because of sea rubbish.

    Studies show that 80%of all the waste is from the land. The waste is mainly plastics (塑料制品) which are really hard to degrade (降解). So the rubbish will remain there for a long time. Some of the pollution is caused accidentally. For example, about 10,000 product-filled boxes are lost at sea every year from business ships. Sometimes people just throw things into the water from boats or land. Many large rubbish areas are formed in the North Pacific Ocean.

    Thankfully, the situation isn't ignored (忽视). Groups like the National Oceanic and Atmospheric Association (NOAA) are taking action to help clean the sea. Since 2006, 76 projects have cleared out 3,814 metric tons (公吨) of rubbish from the sea. Methods of rubbish cleaning include using machines to remove (移除) the waste away from the surface of sea water. Besides, special nets are set by the mouths of rivers to stop the rubbish before it reaches the sea. If everyone does his part, sea rubbish seems like a problem that can be solved.

    Being street smart is an important skill tohave and a good way to take care of yourself.

    Always carry your phone with you, but do notlook at1 whileyou are walking. Being able to communicate or call for help is important, so keepa list of useful numbers. But put your phone away while you are walking so thatyou can keep your2 upand see what's going on around. If you do need to check your phone,3 andlook at it quickly.

    Don't wear earphones4 you are out. If you have to5 something when you're out, use only oneearphone or play it at a very low volume(音量).

    Travel with6 or family members when possible and never go anywherewith a stranger. It's7 tobe careful with strangers. Remember not to get into a stranger's car if they callyou over.

  8 darkand out-of-the-way places. Do not take short cuts through dark areas, even if itwill make your trip much faster. If you have to go to unsafe places, go9 someone you know or speak to someone over the phonewhile you are there.

    Run and shout if you feel unsafe. Run away asfast as you can towards a police station, hospital, or nearby business for10.Shout as loudly as you can to get the attention of people nearby.

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.

Young people often feel unhappy when they are with their parents. They say that their parents don't{#blank#}1{#/blank#} them. They often think their parents are strict with them.

Parents often find {#blank#}2{#/blank#} difficult to win their children's trust and they seem to forget how they felt when they were young.{#blank#}3{#/blank#} example, young people like to do things without much thinking. Older people are worried about things more easily, they need to {#blank#}4{#/blank#} things from many ways. So most of them plan things {#blank#}5{#/blank#} and don't like their plans to be changed.

Young people often make their parents angry by clothes they want to {#blank#}6{#/blank#}, the music they enjoy and something else, they don't really want to make trouble. They feel that in this{#blank#}7{#/blank#} they can be away from the old people's world. They want to make a new culture of their own. But if their parents don't like their {#blank#}8{#/blank#} or clothes, the young people will feel very unhappy.

Sometimes instead of going out with their parents, they {#blank#}9{#/blank#} want to stay at home alone and do what they like.

{#blank#}10{#/blank#} you plan to manage an independent life, you'd better win your parents' trust and try to get them to understand you. If your parents see that you have a high sense of responsibility (责任感) , they will certainly give you chances to do what you want to do.

"I don't like my school, and I want to go home!" Do you have that idea that? A lot of children do. Now let's talk about it.

If you don't like your school, the first thing is to know why. You may not like your teachers. You may not have many friends at school. You may have problems with your subject s or homework

But what can you do with it? You can make some new friends. Going to school can be very interesting if you have many friends at school. You can make friends after school or when doing sports, then you can talk with them and do the same thing with them. You can also make school easy. If you don't like your teachers, you can talk with them. If you think your subjects are boring and difficult, you can ask others for help.

School is not a prison (监狱). You can learn to make your school life easy and interesting.