Have you ever counted the number of digits (数字) in your mobile phone number? Your number has 11 digits. You may sometimes find it hard to remember your number. That's because China has the longest mobile phone numbers in the world. Why is that?

    The 11 digits can be divided into three parts. Each part has a different meaning. The first three numbers tell you which mobile phone service company it is. For example, 135 is for China Mobile Communications Corporation and 188 is for China Unicom. The fourth to the seventh digits tell you where the number is registered (注册). And the last four digits are random (随机的).

    The main reason for using 11 digits is that we have the largest population in the world. We once had 10 numbers. But as our population grew, there were not enough numbers for us to use. So we began to use 11 digits starting from 1999. Eleven digits can be used to make tens of billions of mobile phone numbers. That's enough for each person to have seven or eight phone numbers to use in China.

    And mobile phone numbers can be recycled. Usually, the service company will reuse a canceled number after three to six months. If you call a number that you haven't contacted for a long time, you may find that its owner has changed.

    Besides China, Britain and Japan also use 11-digit mobile phone numbers. But their numbers always start with 0. So they cannot create as many numbers as we can. Countries like the United States, Australia and India use phone numbers with 10 digits. Canada's mobile phone numbers are perhaps the shortest in the world: they use seven digits.

Canadian: In my country, the mobile phone numbers use seven digits. Why does this mobile phone have 11 digits—13958583739?

Salesman: We have the largest population. Besides China, {#blank#}1{#/blank#} also use 11-digit numbers.

Canadian: What do the numbers mean?

Salesman: The number {#blank#}2{#/blank#} tells you which mobile phone service company it is.

    The {#blank#}3{#/blank#} to the seventh numbers tell you the {#blank#}4{#/blank#} of its registration. The number 3739 is random.

Canadian: Can you {#blank#}5{#/blank#} the phone numbers?

Salesman: Yes, after three to six months.

    I will never forget the lesson about my window. Four years ago, I moved to a house in a large town. One of my new neighbors' house was only a few feet away from mine.{#blank#}1{#/blank#} Through one of my windows, I could see her reading by her window every afternoon.

    A few months later, I found I couldn't see the woman clearly. {#blank#}2{#/blank#} I said to myself, "Why doesn't she clean her window? It looks terrible!"

    One afternoon, I decided to clean my house including (包括) the window.{#blank#}3{#/blank#} So I sat down by the window for a rest. What a surprise! I could see the woman reading there clearly again! By that time, I knew that my own window was too dirty, not hers! {#blank#}4{#/blank#} I had been watching her through my dirty window in the past days!

    {#blank#}5{#/blank#} Now I try to clean the window of my heart before judging(评判)others.

He Zhuowen, 14

    Some of us students are still afraid to sleep alone. But my robot can help. It can read stories and sing songs to you when you go to bed. You can have a nice sleep every night with my robot.

Li Zihao, 14

    I'd like to make a robot cleaner. Our parentsare very busy with work, but they still have todo some housework when they get back home. A robot cleaner can help with the housework a lot. Then Mom and Dad can play or talk with us. Isn't that great? Zhang Liaoxing, 13

    All robots should be able to protect their owners. My robot is as powerful as the famous hero Robocop. But it is much smaller. It looks like a student. We go to school together every day. But when there is an emergency (紧急情况), it will protect us students and fight against the bad guys(家伙) at once.

Wang Yuwei, 13

    I often feel lonely, so my robot will be very friendly and kind. It can know your feelings and react (反应) like your friends. I will also let the robot read, so it knows a lot and can teach us about right and wrong, just like our parents. In a word, with my robot, you won't feel lonely any more.