根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。

      Secret codes (密码)keep messages private。Banks, companies, and government agencies use secret codes in doing business, especially when information is sent by computer.

     People have used secret codes for thousands of years. {#blank#}1{#/blank#}  Code breaking never lags(落后) far behind code making. The science of creating and reading coded messages is called cryptography.

     There are threemain types of cryptography. {#blank#}2{#/blank#}  For example, the first letters of “My elephant eats too many eels” Spell out the hidden message “Meet me.”

{#blank#}3{#/blank#} You might represent each letter with a number, For example, Let's number the letters of the alphabet, in order, from 1 to 26. If we substitute a number for each letter, the message “Meet me” would read “13 5 20 13 5.”

     A code uses symbols to replace words, phrases, or sentences. To read the message of a real code, you must have a code book. {#blank#}4{#/blank#} For example “bridge“ might stand for “meet” and “out” might stand for “me.” The message “bridge out” would actually mean “Meet me.” {#blank#}5{#/blank#}  However, it is also hard to keep a code book secret for long. So codes must be changed frequently.

A. It is very hard to break a code without the code book.
B. In any language, some letters are used more than others.
C. Only people who know the keyword can read the message.
D. As long as there have been codes, people have tried to break them.
E. You can hide a message by having the first letters of each word spell it out.
F. With a code book, you might write down words that would stand for other words.
G. Another way to hide a message is to use symbols to stand for specific letters of the alphabet.

How to Win a Debate Competition

    Debating doesn't mean that you can end up arguing with your opponents(对手). {#blank#}1{#/blank#}．The following tips on how to win a debate will further help you out.

    1 ){#blank#}2{#/blank#}

    This is very important. If you already know the debate topic that you are going to debate on, learn as much about it as you can. Research on it and then form opinions about it. Only if you know something in and out, will you be able to talk convincingly on it.

    2 ) Be confident.

    When you are putting your point in front of your opponents as well as the audience, be sure of yourself. Along with the words, your body language, voice modulation (语调) and eye contact, will play a major part in your success in debating. {#blank#}3{#/blank#}

    3 ) Give real life examples.

    While debating, make use of very simple language, which your audience can understand very easily. Give as many real examples as you can when making a point. {#blank#}4{#/blank#}．Thus, the judges and audience will find you much more convincing.

    4 ) Be descriptive.

    To win any debate, there is something about the human mind that you should be aware of. The thing with us humans is that if we see something, we believe and remember it much more than something we merely hear! {#blank#}5{#/blank#}．Tell you point of view in such a way that they can actually "see" what you are saying. If you are somehow able to pull this off, there is no doubt that you will be the winner of the debate competition!

    Follow the tips mentioned above, and with time, you will see yourself winning over your judges and audience.

    Many people think of guys as being carefree when it comes to their appearance. But in fact, a lot of guys spend plenty of time in front of the mirror. {#blank#}1{#/blank#}.

    Body image is a person's opinions and feelings about his or her own body and physical appearance. {#blank#}2{#/blank#} You appreciate your body for its capabilities and accept its imperfections.

    So, what can you do to develop a positive body image? Here are some ideas：

    Recognize your strengths. Different body types are good for different things. Maybe your speed, strength makes you better than others at a certain sport. Maybe basketball, table tennis, or even running or perhaps non－sports skills, like drawing, singing, or acting. {#blank#}3{#/blank#}

    Exercise regularly. Exercise can help you look good and feel good about yourself. Good physiques (体形) don't just happen. {#blank#}4{#/blank#} A healthy habit can be as simple as exercising 20 minutes to one hour three days a week. Working out can also lift your spirits.

    {#blank#}5{#/blank#}.Your body is just one part of who you are. Your talent for comedy, and all the other things make you unique. So try not to let small imperfections take over.

A．Use this as an opportunity to discover what you're good at.

B．Be yourself.

C．They care just as much as girls do about their body image.

D．Just explore talents that you feel good about.

E．They take hard work, regular workouts, and a healthy diet.

F．The good news is that self－image and body image can be changed.

G．Having a positive body image means feeling satisfied with the way you look.

    Steel is a hard metal that people use to make many different products. Car bodies, bridges, building frames, and containers are just a few of the things made from steel. {#blank#}1{#/blank#} But steel is better than iron in many ways. Steel is stronger but lighter than iron. Steel also lasts longer than iron.

    {#blank#}2{#/blank#}Then they add carbon to the liquid iron. They may also add other materials to make different types of steel. For example, steel with added chromium（铬）is called stainless steel. It will not rust（生锈）or stain. Finally, workers use machines to cool the liquid steel into bars or long sheets.{#blank#}3{#/blank#}

    People made the first steel as early as 1400 BC. Ancient people heated iron inside a pile of burning charcoal（木炭）. {#blank#}4{#/blank#}. The result was not the same as modern steel, but it was stronger than regular iron.

    In the 1800s people began to use huge ovens to make large amounts of steel. In the late 1800s builders used steel to make some of the first skyscrapers. {#blank#}5{#/blank#}. In the 1900s new processes made steel-making easier. Today steel remains one of the most popular building materials in the world.

A. This added carbon to the iron.

B. Steel is quite different from iron.

C. The hardened steel may then be made into products.

D. Steel is basically iron mixed with a little carbon.

E. Then they will be cooled and put on the market.

F. To make steel, workers hear iron until it melts.

G. They also used steel to make large, modern bridges.

    When you think about people who have made the world a better place, you probably think of famous scientists or great leaders. That is not all the truth.  {#blank#}1{#/blank#} An act of kindness can bring a smile to a person's face even if only for a moment.

    Give away your money.  {#blank#}2{#/blank#} For example, if you want to help hungry children, you can try to find an international organization that provides food for those in poor areas. Every cent you give away will mean a lot.

    Help a stranger. Your small actions can brighten the day of others. Hold the door for someone whose hands are full. Help the blind cross the street.  {#blank#}3{#/blank#} The key is expecting nothing in return for your acts of kindness.

    Care about those you know. Show the people close to you how much you care about them. Tell them they mean a lot to you. Make a beautiful gift for a friend. Take your husband to his favorite fun place if he has had a hard week.  {#blank#}4{#/blank#}

    Be grateful to others. Have you had good service in a restaurant？Thank the waiter. Do you have a very good neighbour who is always there when you need her？Tell her how much you appreciate her being in your life.

    {#blank#}5{#/blank#} If a friend needs skills in a certain area, offer your advice. Perhaps she is struggling to set up a computer, and you know how to do that. Offer whatever ability you have, but always remember to be polite.

A. Keep walking forward.

B. Share your knowledge.

C. Small steps, not big ones.

D. Give your seat on the bus to an old man.

E. Choose a charity that has meaning for you.

F. Tell your children how much they mean to you.

G. Ordinary people like you and me can also help a lot.

    Homework is made up of out­of­class activities and at­home activities teachers assign to students. It can include practice assignments that emphasize newly acquired skills. {#blank#}1{#/blank#} Projects that have to be worked on in agreement with schoolwork also form a part of homework.

    {#blank#}2{#/blank#} For example, to complete their homework in time, children start dividing their time into studying and playing, thus learning to complete their scheduled tasks within the time they have. They learn to do things on their own. They manage their time and complete their work independently.

    Homework can also help build up children's confidence. {#blank#}3{#/blank#} Teachers' positive remarks can help develop students' confidence and encourage them to keep up with their good work.

    In addition, homework gives students a chance to learn from their mistakes and overcome their weakness. It provides them with a platform to express what they know or have newly found, and exhibit their talents.{#blank#}4{#/blank#} This helps them improve their academic results.

    However, to be as beneficial to students as possible, homework should be assigned properly. The amount and difficulty level of homework assignments should match the ages and abilities of students.{#blank#}5{#/blank#} Homework proves to be beneficial only if it does not put students under stress or pressure.

A. Otherwise, it will become a punishment.

B. Homework can benefit students in many ways.

C. Teachers give comments on the work that students do.

D. It also gives students the practice of whatever they learn in school.

E. Completing homework requires planning, organizing and acting upon it.

F. Students can gain a sense of accomplishment after completing homework.

G. It can be preparation assignments to make students ready for class activities.