学进去

Wang Wei is a middle school student. He lives in Shanghai. He 1． (live) here since he was three years old. Every day he 2． (go) to school by bike. He has a very beautiful bike. His uncle 3． (give) it to him on his tenth birthday. He 4． (have) it for four years. He 5． (not be) to a foreign country before. Next week he will go to Singapore with his parents. They plan 6． (stay) in Singapore for a week. “ Traveling to Singapore is a dream for me for a few months,” Wang Wei said to his friend Jim. “ It 7． (come) true soon.” He wants to visit the “Night Safari”. He also wants to try Chinese food in Singapore.

期末考试前后，很多同学对自己的学习产生了不同程度的心理焦虑情绪。请你给同学们提出几条合理性的建议，帮助他们调适心情。

It’s hard to turn down junk food. However, eating too much is bad for your body, especially if you’re between the ages of 10 and 19. “Junk food shapes teenage brains in ways that make their ability to think, learn and remember weaker. It can also make it harder to control bad behaviors. It may even up a teen’s risk of mental (精神上的) problems,” said Amy Reichelt, a scientist at Western University, Canada.

Reichelt and two other researchers reviewed more than 100 studies about how poor food choices can make a big difference to teenage brains. They found teenagers are more sensitive (敏感的) than any other age group to foods with a lot of fat and sugar, as their brains are not yet fully formed.

Teenage brains are still developing the ability to notice risks and control actions. The prefrontal cortex (前额皮质) is the part of the brain tells us we shouldn’t eat chips all the time and helps us control ourselves. However, this part doesn’t fully develop until we are in our early 20s. At the same time, teen brains get more excited from prizes. The parts of the brain that make us feel good when we do something happy—like eating tasty foods—are fully developed by the teen years.

As a result, the teen brain has two hits against it when it comes to refusing junk food. Reichelt and her team did an experiment using mice, whose brains develop much like our own. They discovered that “teenage” mice that had high-fat foods performed worse on memory tests than those eating normal foods.

So, what’s the best way to say no to junk food? The answer is exercise. When we exercise, the brain becomes less sensitive to food, besides this, it also helps our brains grow and become better able to make wise decisions.

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How could we tell time if there were no watches or clocks anywhere in the world? The sun was probably the world’s first “clock”, except in the far north, where the Eskimos(爱斯基摩人) live. There, it’s dark most of the winter, and light most of the summer. But in most of the world, people have used the sun for a clock. Even today, if you don’t have a clock, you still know that when the sun shines, it’s day, and when it’s dark, it’s night. The sun can also tell you if it’s morning, noon, or afternoon.

People who live near the sea can tell time from the tides. In the daytime, for about six hours, the water rises higher and higher on the beach. And then it goes down and down for about six hours. The same thing happens again at night. There are two high tides and two low tides every 24 hours.

Seamen on a ship learn how to tell time by looking at the moon and the stars. The whole sky is their clock.

In some places in the world the wind comes up at about the same time every day or changes direction or stops blowing. In these places the wind can be the clock.

A sand clock is an even better clock. If you had fine dry sand in a glass shaped like the one in the picture, you would have what is called an hourglass. The sand in the hourglass goes from the top part to the bottom part in exactly one hour. When the hourglass is turned over, the sand will take another hour to go back again.