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 Study English In China

    English is obviously not the native language in China. Although many Chinese want to improve their English level to the amount needed in daily work, it's very hard when only a few people speak English around them. {#blank#}1{#/blank#} Here are a few tips that might help.

Join a school with native teachers to guide you.

    {#blank#}2{#/blank#} The more exposure you can get to these foreign teachers, the faster and better you're going to learn English. If a school doesn't give students maximum exposure to native English speakers' classes, find one that does.

Read English daily.

    This means using websites that are permitted in China, accessing English texts, newspapers and books. Read short stories in English. When you come across words you don't know write them down immediately. {#blank#}3{#/blank#}

Find some English speakers.

    Spend time with them and share conversations. There is nothing better for learning any language than finding native speakers of the language to practice with. When you speak, you are practicing every aspect of the language(except writing) in the most efficient way possible.

Memorize vocabulary.

    Write new words in a notebook every week, with English definitions and a sample sentence, not a Chinese translation. {#blank#}4{#/blank#} Carry it with you everywhere you go. Even if you have a question about something that you see and you don't know the English word, write it down in your own language with the plan to look it up later and learn that word in English.

    {#blank#}5{#/blank#} English is not well controlled by grammar rules. For every rule, there is an exception to that rule. Your time will be better spent in watching movies and learning from them than studying grammar for long hours. Find someone to write emails in English to or write a dairy every day.

    There are many other ways to improve your English. Come on!

A. Learn to write.

B. Watch an English film once a month.

C. What can you do to study more English?

D. There are many English speakers in China.

E. You can do this by writing in your notebook.

F. Follow a soap opera, comedy or radio program or TV drama.

G. You should be carrying a notebook with you everywhere you go just to write down something important.

    It is difficult for parents of nearly every family to teach their children to be responsible for housework, but with one of the following suggestions, you really can get your children to help at home.

    If you give your children the impression that they can never do anything quite right, then they will regard themselves as unfit or unable persons. Unless children believe they can succeed, they will never become totally independent.

    My daughter Carla's fifth-grade teacher made every child in her class feel special. When students received less than a prefect test score, she would point out what they had mastered and declared firmly they could learn what they had missed.

     You can use the same technique when you evaluate (评价) your child's work at home.

    Don't always scold and give lots of praise instead. Talk about what he has done right, not about what he hasn't done. If your child completes a difficult task, promise him a Sunday trip or a ball game with Dad.

    Learning is a process of trying and failing and trying and succeeding. If you teach your children not to fear a mistake of failure, they will learn faster and achieve success at last.

    There was a gardener who looked after his garden with great care. To water his flowers, he used two buckets(水桶). One was a shiny and new bucket. The other was a very old and dilapidated one, which had seen many years of service, but was now past its best.

    Every morning, the gardener would fill up the two buckets. Then he would carry them along the path, one on each side, to the flowerbeds. The new bucket was very proud of itself. It could carry a full bucket of water without a single drop spilled (溢出). The old bucket felt very ashamed because of its holes: before it reached the flowerbeds, much water had leaked（泄漏）along the path.

    Sometimes the new bucket would say, “See how capable I am! How good it is that the gardener has me to water the flowers every day! I don't know why he still bothers with you. What a waste of space you are!”

    And all that the old bucket could say was, “I know I'm not very useful, but I can only do my best. I'm happy that the gardener still finds a little bit of use in me, at least.”

    One day, the gardener heard that kind of conversation. After watering the flowers as usual, he said, “You both have done your work very well. Now I am going to carry you back. I want you to look carefully along the path.”

    Then the two buckets did so. All along the path, they noticed, on the side where the new bucket was carried, there was just bare (光秃秃的) earth; on the other side where the old bucket was carried, there was a joyous row of wild flowers, leading all the way to the garden.

    When introducing American universities, some of the first institutions to mention are the Ivy League schools. Originally, the Ivy League was an athletic conference made up of 8 private institutes of higher learning in northeastern United States. However, as time went on, these schools also became known for their excellence in academics besides athletics. Included in the Ivy League schools are Brown University, Columbia University, Cornell University, Dartmouth College, Princeton University, University of Pennsylvania, Yale University, and Harvard University. These 8 schools have been recognized as some of the best colleges and universities in the United States.

    Harvard University is a private institution located in Cambridge, Massachusetts. The university includes a number of graduate and professional schools, as well as a college for undergraduates. In 2012, Harvard ranked number one in US News' ranking of national universities again. Founded in 1636, Harvard is the oldest institute of higher education in the United States. It can be said that first there was Harvard, then the United States of America. Also, Harvard's library contains the oldest collection of books in the United States as well as the largest private collection in the world. Harvard has also been described by Forbes Magazine as one of the “billionaire universities” as of their recent list of 469 billionaires, 50 received a degree from Harvard.

    Harvard College (the institute for undergraduate students) is one of the most famous schools in the United States. It offers over 40 undergraduate fields of study, including astrophysics(天体物理学), mathematics, neurobiology(神经生物学), etc. And the financial aid program there is amazing. Even though the tuition is about $ 37,576, and there are other expenses throughout the year, about 70% of undergraduate students received financial aid. Out of those students, over 90% of them had their full need met. And the policies for international students are the same for U.S. citizens.

    Harvard College is very selective, as it only admits about 6% of their applicants. For admission into Harvard College, it is required that students take the SAT or the ACT, as well as SAT Subject Tests. Harvard will also look at other factors during admission such as your application essay, high school transcript, work experience, GPA (Grade Point Average), your interview, recommendations, and most importantly, your character and personal qualities.

    Age has never been a problem for 16­year­old Thessalonika Arzu­Embry. After all, she's already got her master's degree.

    The North Chicago­area teen started homeschooling at the age of 4. She began having an influence on others soon after. When she was 6 years old, she was an inspirational speaker at an organization called Tabitha House Community Service, a shelter for people who were forced to leave their homes due to the situations such as earthquake, flood and other natural disasters.

    At the age of 11, she graduated from high school and then earned her bachelor's degree in psychology in 2013. She completed those classes online as she was traveling for church events and leadership meetings.

    She doesn't stop there, though. The teen plans to focus on aviation psychology(航空心理学) for her further study, a decision inspired by her father who is a pilot. She grew up around airplanes and took fights all the time. Her goal is to use it to determine whether pilots are dealing with problems that could have deadly results once the plane takes off­a topic that has been in the news lately. For her, it's a mix of two of her interests.

    In her free time, Thessalonika enjoys playing tennis, swimming and being active in her youth group at church. She also has three self­published books, which are on her site. Jump the Education Barrier is written to help students finish college, and in the future aims to help business owners with trends. Her third book The Genius Race, has a wider appeal. It is designed to help people to be geniuses in various areas of life.