Most people around the world are right-handed. This also seems to be true in history. In 1799, scientists studied works of art made at different times from 1,500 B.C. to the 1950s. Most of the people shown in these works are right-handed, so the scientists guessed that right-handedness has always been common through history. Today, only about 10% to 15% of the world's population is left-handed.

Why are there more right-handed people than left-handed ones? Scientists now know that a person's two hands each have their own jobs. For most people, the left hand is used to find things or hold things. The right hand is used to work with things. This is because of the different work of the two sides of the brain. The right side of the brain, which makes a person's hands and eyes work together, controls the left hand. The left side of the brain, which controls the right hand, is the centre for thinking and doing problems. These findings show that more artists should be left-handed, and studies have found that left-handedness is twice as common among artists as among people in other jobs.

No one really knows what makes a person become right-handed instead of left-handed. Scientists have found that almost 40% of the people become left-handed because their main brain is damaged when they are born. However, this doesn't happen to everyone, so scientists guess there must be another reason why people become left-handed. One idea is that people usually get right-handed from their parents. If a person does not receive the gene (基因) for right-handedness, he / she may become either right-handed or left-handed according to the chance and the people they work or live with.

Though right-handedness is more common than left-handedness, people no longer think left-handed people are strange or unusual. A long time ago, left-handed children were made to use their right hands like other children, but today they don't have to.

Here is a story: A man sees a butterfly (蝴蝶) . The butterfly tries to get out of its chrysalis (蛹) . F{#blank#}1{#/blank#}sorry for it, the man decides to help. He cuts the chrysalis and the butterfly comes out e{#blank#}2{#/blank#}. Surprisingly enough, the butterfly is unable to fly. If the butterfly doesn't struggle (挣扎；奋斗) to leave the chrysalis, it can't fly！The struggle develops the e{#blank#}3{#/blank#} in the butterfly which makes it fly. Similarly, the challenges of life bring out the best in young people and make the fly.

When people are young, meeting and overcoming challenges will make them s{#blank#}4{#/blank#} and ready to face life.

When we look at successful people, we see that the most successful of them are people who have had to struggle.

One famous businessman, who now o{#blank#}5{#/blank#}many big supermarkets, used to carry clothes on his back and sell them from door to door when he was young. Another successful man is Dennis. His father died when he was only twenty. He had to b{#blank#}6{#/blank#}up a big family. He took up the challenges and overcame them. Today his brothers and sisters are leading s{#blank#}7{#/blank#} lives.

Sometimes challenges do not appear to us because we keep away from them. So, some parents and teachers actively encourage young people to face challenges. They might organize some a{#blank#}8{#/blank#}for young people which provide them with challenges, like rock—climbing, camping, volunteer work and so on. However, just passing exams will not prepare a person for life. We must meet and overcome challenges. The young people of today will become the leaders of t{#blank#}9{#/blank#}. For countries to continue to become successful, it is i{#blank#}10{#/blank#}that the young people learn to meet challenges and overcome them.

    Water is very important to us. Every day we drink water, cook with water, take a shower in water, and have many other activities with water. Let's read and learn more about it!

    70percent of an adult's body is water. And about 80percent of a baby's body is water.

    Drinking too much water q{#blank#}1{#/blank#} can cause water intoxication (醉).

People should have about eight c{#blank#}2{#/blank#} of water every day.

    By the time you feel thirsty, your body has l{#blank#}3{#/blank#} over one percent of its water.

    About 80percent of the Earth's surface is covered with water.

    Only one percent of this water is fresh, 97percent is salt water and two percent is f{#blank#}4{#/blank#} in glaciers (冰川).

    And now, it's time to s{#blank#}5{#/blank#} water!

Chongyang Festival {#blank#}1{#/blank#} (celebrate) on the ninth day of the ninth month on the traditional Chinese calendar, and it is also known as Double Ninth Festival.

In Chinese culture, the number nine is thought to be yang. The ninth day of the ninth month is a double yang day and "double"{#blank#}2{#/blank#} (mean) Chong in Chinese, so it got the name Chongyang Festival. The ninth month also heralds（预示）the coming of winter, so it is a time when the living need warm clothes, and some people make the festival a time for {#blank#}3{#/blank#} (provide) special clothes for their ancestors（祖先）.

During the festival, people usually {#blank#}4{#/blank#} (climb) mountains, wear the zhuyu plant, drink chrysanthemum (菊花) wine, and eat Chongyang cake. Cake in Chinese is pronounced "gao" meaning high, so people consider climbing a high mountain to be the same as eating cake. Also, people think they {#blank#}5{#/blank#} (do) better than before after eating the cake.

Double Ninth Festival is also Seniors' Day— a day to care for the elder people and to let them {#blank#}6{#/blank#} (enjoy) themselves. On the day, many communities organize retired people to go out {#blank#}7{#/blank#} (climb) mountains.

A tornado (龙卷风) is a kind of strong storm with air which moves in a circle quickly. They can move over 200 miles per hour and cause a lot of damage (损坏). As they move across the land, they can easily pick up cars, trucks, and even houses, and then throw them very far. It is important to find a safe place if a tornado gets close.

A safe place could be a basement ( 地下室) or the lowest floor. If you are in a home without a basement, try to find a first-floor bathroom or a small room without windows in the middle of your house. You should curl up (蜷缩) into a ball and cover your head and neck with your hands.

But there are some people who actually want to get close to tornadoes. They are scientists who want to learn more about tornadoes. One of the best ways to do this is to get as close as possible to the tornado. They use special tools to measure (测量) what is happening in and around a tornado.

One special tool is called a tornado probe ( 探测仪). Inside the tornado probe, there are sensors (传感器) to measure wind speed, temperature, pressure, and direction.

Some probes even have cameras, so the scientists can see and understand what it's like to be in a tornado.

To be able to get these measurements, the scientists have to get a tornado probe near or into a tornado. Scientists will try to guess where a tornado will go next. Then they drive to that location and put down the probe. If they do not guess correctly, they pick up their probe and try another place. If they are right, the tornado will go near or even right over the probe. Then they take all of the measurements

from the probe and use them to predict where future tornadoes may form (形成) and travel. And they can give people some warning to keep away from a dangerous tornado.

    If you had billions of dollars, would you donate almost all of it to charity? Well, that's what Mark Zuckerburg, CEO and founder of Facebook, just said he would do.
    Zuckerburg and his wife Priscilla Chan promised to give 90% of their Facebook shares to society. Right now that is about $45 billion, and they plan to donate the money to things like science and education.
    Many billionaires have done similar things. Bill Gates, creator of Microsoft, made The Giving Pledge, an activity in which billionaires promise donate more than half of their wealth to charities. This started in 2010, and now 139 people from 15 countries joined it.
    But giving back and helping others isn't just for big billionaires. People like Zuckerberg, and Gates may have more to give, but people with less are doing it, too.
    Especially around the holidays, people want to do their part and give back to people who are less lucky than them. Schools may have food collections where people bring a few food items, and together they can make a big donation to places like homeless people's homes.
    People also host special events like concerts of runs to be creative while raising money. Regular people donate whatever they can to US charities like the United Way and the American Red Cross.
    Then these charities are able to help US communities in different ways like education, health and improving the lives of the poor. These individual donations come together to make a big difference.