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.

"Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid."—Albert Einstein

If you have a kid with special needs in the school system, chances are you have come across that saying hanging on a classroom wall. My five-year-old daughter Syona has cerebral palsy (a medical condition affecting someone's control over their movement ) and it means, combined with her communication challenges and sight problems, that standard assessments (and by "standard", I mean the ones used to assess kids with special needs ) aren't always an accurate measure of her abilities.

By now you have probably heard about Chris Ulmer, the 26-year-old teacher in Jacksonville, Florida, who starts his special education class by calling up each student individually to give them much admiration and a high-five (a gesture of greeting or congratulation). I couldn't help but be reminded of Syona's teacher and how she supports each kid in a very similar way. Ulmer recently shared a video of his teaching experience. "I have seen their confidence and self-worth increase rapidly, " he said. All I could think was: How lucky these students are to have such inspirational teachers.

    Syona's teacher has an attitude that can best be summarized in one word: awesome. Her teacher doesn't focus on what can't be done—she focuses on what can be done. Over the past several months, my husband Dilip and I have seen Syona's confidence increase tenfold. She uses words she wouldn't have thought of using before. She recently told me about her classmate's trip to Ecuador and was very proud when I understood her on the first try.

    I actually wonder what the influence would be if we did something similar to what Ulmer does with his students in our home. We've recently started our day by reminding each other of the good qualities we all possess. If we are reminded of our strengths on a regular basis, we will become increasingly confident about progress and success.

    Ulmer's reach as a teacher goes far beyond the walls of his classroom. In fact, he teaches all of us to take a moment and truly appreciate the strengths of an important person in our lives.

    It was a winter morning,just a couple of weeks before Christmas 2005.While most people were warming up their ears,Trevor,my husband,had to get up early to ride his bike four kilometers away from home to work.On arrival, he parked his bike outside the back door as he usually does.After putting in 10 hours of labor,he returned to find his bike gone.

    The bike,a black Kona 18 speed,was our only transport（交通工具）.Trevor used it to get to work,putting in 60-hour weeks to support（养活）his young family.And the bike was also used to get groceries（食品杂货）saving us from having to walk long distances from where we live.

    I was so said that someone would steal our bike that I wrote to the newspaper and told them our story.Shortly after that,several people in our area offered to help.One wonderful stranger even bought a bike,then called my husband to pick it up.Once again my husband had a way to get to and from his job.It really is an honor（幸事）that a complete stranger would go out of their way for someone they have never met before.

    People say that a smile can be passed from one person to another,but acts of kindness from strangers are even more so.This experience has had a spreading effect in our lives because it strengthened our faith in humanity（人性）as a whole.And it has influenced（影响）us to be more mindful of ways we,too,can share with others.No matter how or how small,an act of kindness shows that someone cares.And the results can be everlasting.

    Using too much water or throwing rubbish into our rivers are clear ways that humans can put our water supply in danger , but we also affect our water supply in less obvious ways. You may wonder how paving(铺砌) a road can lead to less useable fresh water. A major part of the water we use every day is groundwater. Groundwater does not come from lakes or rivers. It comes from underground. The more roads and parking lots we pave ，the less water can flow into the ground to become groundwater.

    Human activity is not responsible for all water shortages(短缺). Drier climates are of course more likely to have droughts(干旱) than areas with more rainfall, but in any case, good management can help to make sure there is enough water to meet our basic needs.

    Thinking about the way we use water every day can make a big difference, too In the United States , a family of four can use 1.5 tons of water a day! This shows how much we depend on water to live, but there's a lot we can do to lower the number.

    You can take steps to save water in your home. To start with use the same glass for your drinking water all day. Wash it only once a day. Run your dishwasher (洗碗机)only when it is full 。Help your parents fix any leaks in your home. You can even help to keep our water supply clean by recycling batteries instead of throwing them away.

    London's transport services offer you a special experience of the city. Here's a round-up of the transport choices available to you.

    London Underground

    There are 11 colour-coded Underground lines. Services run regularly from around 05:00 to 00:30 (Sunday 07:30 to 23:30) on most routes.

Visit tfl.gov.uk/tube for more information.

    Tip:

    Always stand on the right when using the escalators (电动扶梯) at Tube stations. It can get hot and busy on the Tube during peak (高峰) travel times, so you may prefer to travel outside these hours.

    Buses

    A cheap and easy way to travel around London. They generally run from 05:00 to 00:30. Night buses operate on many major routes from around midnight to 05:00, and some operate a 24-hour service.

    It is not possible to pay for your London bus fare in cash. Instead you can pay with a Visitor Oyster card, Oyster card, Travelcard or UK-issued contactless payment card. A single bus journey is £1.50 with an Oyster card or UK-issued contactless payment card.

    To help you get home, if you don't have enough credit on your Oyster card, you will be able to make one more bus journey.

    After this you will need to top up the credit on your card before you use it again. If your contactless payment card has been issued outside the UK, please check tfl.gov.uk/contactless before you use your card to travel on our bus services. For any international transaction fees (手续费) that may apply, please check with your card issuer.

    For more information visit tfl.gov.uk/buses.

    Tip:

    Some bus routes are especially good for sightseeing — try routes 9, 14, 15 and 22. The New Routemaster bus featured in the James Bond film Skyfall and runs on routes 9, 11, 24, 38 and 390.

    If you run out of credit on your Visitor Oyster card, it's easy to add more at:

    Touchscreen ticket machines in Tube, DLR, London Overground and some National Rail stations.

    Around 4,000 Oyster Ticket Stops cross London (Find your nearest one at ticketstoplocator.tfl.gov.uk).

    Travel & Visitor Information Centres.

    London Overground station ticket offices.

    Scientists, psychologists and English academics at Liverpool University have found that reading the works of the classical writers like Shakespeare and Wordsworth has a great effect on the mind, catches the reader's attention and triggers moments of self-examination.

    Using a special machine, they monitored the brain activity of 30 volunteers as they read works by William Shakespeare, William Wordsworth, T.S. Eliot and others.

    In the first part of the research, the brain activity of 30 volunteers was monitored as they read passages from Shakespeare's plays, including King Lear, Othello, Coriolanus and Macbeth, and again as they read the text rewritten in a simpler form or modern language.

    While reading the common texts, normal levels of electrical activity were shown in their brains. When they read the works of Shakespeare, however, the levels of activity jumped because of his use of words which were unfamiliar to them. The result of the test showed that the more challenging passages cause a greater degree of electrical activity in the brain than the common ones.

    Scientists went on to study the brain activity as it responded to each word and recorded how it lit up as the readers came across unusual words, surprising phrases or difficult sentences in the classical works. As a result, this lightening up process of the mind lasted longer than that when volunteers read common texts, encouraging further reading.

    The research also found that reading poetry especially increases activity in the right hemisphere (半 球) of the brain, an area connected with" autobiographical memory", driving the readers to think carefully about their own experiences based on what they have read. The academics said this meant the classical works of literature are more useful than self-help books.

    Philip Davis, an English professor who has worked on the study in the university's magnetic resonance center, announced this week:" Classical literature acts like a rocket-booster to the brain, which provides extra power for the brain. You may never imagine how powerful it is. The research shows such kind of literature can create new thoughts and connections in the young and the old."