If you can find a tree which has been cut down，you will see many rings，or circles，on the base of the trunk.By learning to read these rings，you can find out about the tree's life.

    The number of rings tells you how old the tree is.Each year，new wood is formed on the outside of the tree.This new wood is light in color when the tree is growing in spring and summer，and dark in winter when the tree is not growing much.So，if you count the rings of dark­or­light colored wood，you can often find out how old the tree is.

    You can also tell which years have been good years and which years have been bad years.When the light­colored rings are very wide，it means that the tree has been growing quickly that year.If the rings are narrow，it has been growing slowly.If the rings on a tree trunk were greatly magnified，you would be able to see why the rings are light­colored when the tree is growing quickly and dark­colored when the tree is growing slowly.The tree trunk is made up of microscopic tubes，like some pipes，carrying water from the soil，through the trunk，and up to the leaves.They are wide and thin­walled when the tree is growing quickly and they are carrying a lot of water.They are narrow and stuck together when the tree is not growing so quickly.

    When a tree is old，the tubes in the centre of the tree don't carry water.The walls of the tubes have become thick with materials which have stuck along them over the years，forming a kind of wood called“heartwood”．This kind of wood is darker in color than the young，growing wood on the outside of the tree.

    You don't very often see whole tree trunks which have been cut across.But once you learn to read a cross section of the wood，you can see much more in wood which has been used to make boxes，houses and other things.

    In most wood，instead of seeing the trunk cut across，you are seeing it cut along its length.Because you don't see the whole tree，you can't tell how old it is.

Title：{#blank#}1{#/blank#} of a Tree

    Many of us invest valuable time，energy and money planning our vacations. We do this because we know for sure that going on vacations must be good for us. Research proves this feeling without a doubt. Vacations help us perform better at work, improve our sleep quality and cushion us against depression.

    Yet, despite these benefits, many of us return home with a feeling that our last vacation was OK - but not great. In order to change this, some mistakes should be avoided. A classic one for vacation planners is attempting to maximize value for money by planning trips that have too many components (组成部分)• Perhaps you're planning a trip to Europe, seven cities in 10 days，and you realize it will cost only a little more to add two more destinations to the list Sounds fine in theory, but hopping from one place to the next hardly gives an opportunity to experience what psychologists call mindfulness - time to take in our new surroundings, time to be present and absorb our travel experiences. Another mistake is that we worry too much about strategic issues such as how to find a good flight deal，how to get from A to B，or which destinations to add or subtract from our journey. These issues may seem important, but our psychological state of mind is far more important.

    Actually, vacation happiness is based on the following top rules. First, choose your travel companions wisely, because nothing contributes more significantly to a trip than the right companions. Second，don't spend your vacation time in a place where everything is too expensive so as to maintain a positive mood. Third, shop wisely, for meaningful experiences provide more long-term happiness than physical possessions.

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    Meet Thomas Wilson. Thomas is famous all over the world. He holds the world record for sleeping in (睡过头). One weekend, Thomas slept in for two days, three hours and fourteen minutes. It was unbelievable. No one in history had ever slept in for so long before.

    Thomas was very proud of his world record. His friends were proud of him, too. Whenever Thomas walked down the street, people always came up to him and shook his hand. Thomas was a star.

    The on]y who wasn't proud of Thomas's world record was his father. Dad didn't like it when Thomas slept in. He complained that whenever Thomas slept in, the lawns didn't get mowed. He was worried about how high the grass was getting. Every weekend, it seemed to get higher and higher. “It's like a jungle there,” Dad moaned (抱怨) to Thomas one day. But Thomas wasn't worried about the grass getting higher. He had more important things on his mind—like sleeping in.

    One morning, Thomas was woken from a deep sleep by a loud roaring noise. It sounded like a wild animal pacing about under his bedroom window.

    Thomas rushed over to the window and pulled the curtains back. His eyes bulged like basketballs. “What on Earth…?” He gasped. There, in the middle of the backyard, was a lion! “Awesome!” cried Thomas. Suddenly, a giraffe poked its head through the window. It munched the leaves from a plant sitting by Thomas's bed. Next, an elephant walked past the swimming pool and squirted (喷出) water all over Dad's car! “Cool!” cheered Thomas. “Now I don't have to wash Dad's car today.”

Easy Ways to Keep Your Brain Sharp

    Everyone is forgetful, but as we age, we start to feel like our brains are slowing down a bit—and that can be a very annoying thing.{#blank#}1{#/blank#}Read on for some techniques worth trying.

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    People who regularly made plans and looked forward to upcoming events had a 50 percent reduced chance of Alzheimer's disease (早老性痴呆症), according to a recent study.{#blank#}3{#/blank#}Something as simple as setting a goal to have a weekly coffee date with a friend will do. There's evidence that people who have a purpose in life or who are working on long or short-term goals appear to do better. In other words, keep your brain looking forward.

    ⒉ Go for a walk

    Mildly raised glucose (葡萄糖) levels can harm the area of the brain that helps you form memories and physical activity can help get blood glucose down to normal levels. In fact, exercise produces chemicals that are good for your brain.{#blank#}4{#/blank#}

    ⒊ Learn something new

    Take a Spanish class online, join a drawing club, or learn to play cards. A study found that mental stimulation (刺激) limits the weakening effects of aging on memory and the mind. But the best thing for your brain is when you learn something new and are physically active at the same time.{#blank#}5{#/blank#}or go dancing with your friends.

A. Focus on the future.

B. This can be especially harmful to the aged.

C. It should be something like learning gardening.

D. So take a few minutes each day to do some reading.

E. But don't worry if your schedule isn't filled with life-changing events.

F. Luckily, research shows there is a lot you can do to avoid those moments.

G. In other words, when you take care of your body, you take care of your brain.

    Every animal sleeps, but the reason for this has remained foggy. When lab rats are not allowed to sleep, they die within a month.{#blank#}1{#/blank#}

    One idea is that sleep helps us strengthen new memories. {#blank#}2{#/blank#} We know that, while awake, fresh memories are recorded by reinforcing (加强) connections between brain cells, but the memory processes that take place while we sleep have been unclear.

    Support is growing for a theory that sleep evolved so that connections between neurons (神经元) in the brain can be weakened overnight, making room for fresh memories to form the next day.{#blank#}3{#/blank#}

    Now we have the most direct evidence yet that he is right.{#blank#}4{#/blank#} The synapses in the mice taken at the end of a period of sleep were 18 per cent smaller than those taken before sleep, showing that the connections between neurons weaken while sleeping.

    If Tononi's theory is right, it would explain why, when we miss a night's, we find it harder the next day to concentrate and learn new information — our brains may have smaller room for new experiences.

    Their research also suggests how we may build lasting memories over time even though the synapses become thinner. The team discovered that some synapses seem to be protected and stayed the same size. {#blank#}5{#/blank#} "You keep what matters," Tononi says.

A. We should also try to sleep well the night before.

B. It's as if the brain is preserving its most important memories.

C. That's why students do better in tests if they get a chance to sleep after learning.

D. Similarly, when people go for a few days without sleeping, they get sick.

E. The processes take place to stop our brains becoming loaded with memories.

F. Tononi's team measured the size of these connections, or synapses, in the brains of 12 mice.

G. "Sleep is the price we pay for learning," says Giulio Tononi, who developed the idea.

    Life is not easy when you are looking for something worthwhile and ready to learn from the best experiences. {#blank#}1{#/blank#} Here are some life lessons which people will learn the hard way in majority of cases.

    {#blank#}2{#/blank#}However people usually get discouraged when it takes more time than they thought it would. At this time, people refer only to people who have already achieved what they want to do. Look at any successful person and you'll notice one thing common in all of them: they took time to learn and mastered their skill like no one else. There is no elevator to success and you have to take the stairs.

    Be brave to take the road less traveled. In our whole life, we always want to follow the same path that everyone suggests, do the same thing everyone does, take the same career path everyone takes, wear the same clothes everyone wears, and hang out with the same people we work with. Why? Because we are scared to fail. But when you get bored of life, you realize that you are not meant to do what everyone does and that your destiny is different from anyone else's out there in the world. {#blank#}3{#/blank#}

    You don't have to live your life in a way society wants you to. {#blank#}4{#/blank#}Parents sometimes force their children to select a career they don't want because other children have selected that career. Worst of all, people follow them without even asking. There is no harm in believing in old beliefs but when you pursue them before your interest, sooner or later you'll realize that you should first do what you think is right.

A. It takes continuous time and effort to be successful in any area.

B. The general rule goes that the harder you try, the greater results you get.

C. Many old beliefs are being performed these days and are followed blindly.

D. It always takes tests and then fails us to learn anything worthwhile.

E. However, in most circumstances your effort and attempt go well alongside with your desired achievement.

F. But the price we pay to realize this is high because it takes a great amount of courage to follow your own path.