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.

    It's normal to wake briefly during the night. {#blank#}1{#/blank#}But if you're waking up during the night and having trouble falling back asleep, the following tips may help.

    Stay out of your head. The key to getting back to sleep is continuing to prepare your body for sleep, so remain in bed in a relaxed position. Hard as it may be, try not to stress over the fact that you're awake , because that very stress and anxiety encourage your body to stay awake. {#blank#}2{#/blank#}

    {#blank#}3{#/blank#} If you are finding it hard to fall back asleep, try a relaxation technique such as visualization, deep breathing, or meditation, which can be done without even getting out of bed. Remind yourself that although they're not a replacement for sleep, rest and relaxation still help refresh your body.

    Do a quiet, non-stimulating activity. If you've been awake for more than 15 minutes, try getting out of bed and doing a quiet, non-stimulating activity, such as reading a book. Keep the lights dim so as not to think that it's time to wake up. {#blank#}4{#/blank#} A light snack might help relax you, but be careful not to eat so much that your body begins to expect a meal at that time of the day.

    {#blank#}5{#/blank#} If you wake during the night feeling anxious about something, make a brief note of it on paper and postpone worrying about it until the next day when you are fresh and it will be easier to resolve.

    A student's life is never easy. {#blank#}1{#/blank#} A lot of preparations are needed so you can be sure to go back home with a diploma and a bright future waiting for you. The following are some basic things you need to do before even seizing that passport and boarding on the plane.

Knowing the country.

    You shouldn't bother researching the country's hottest tourist spots or historical places. You won't go there as a tourist, but as a student. It'll be helpful to read the most important points in their history and to read up on their culture. {#blank#}2{#/blank#} You surely don't want to face legal problems, especially if you're away from home.

Studying their language.

    Don't expect that you can graduate abroad without knowing even the basics of the language. Before leaving your home country, take online lessons to at least master some of their words and sentences. {#blank#}3{#/blank#} Doing this will also prepare you in communicating with those who can't speak English.

{#blank#}4{#/blank#}.

    Check the conversion（兑换）of your money to their local currency, set up your bank account so you can use it there, get an insurance, and find an apartment. The Internet or your intended school will be very helpful in finding an apartment and helping you understand local currency.

    Remember, you're not only carrying your own reputation but your country's reputation as well. If you act foolishly, people there might think that all of your country men are foolish as well. {#blank#}5{#/blank#}

A. Packing your clothes.

B. Preparing for other needs.

C. Most importantly, read about their laws.

D. This will be useful in living and studying there.

E. That would surely be a very bad start for your study abroad program.

F. Going with their trends will keep it from being too obvious that you're a foreigner.

G. And it is even more difficult if you will have to complete your study in a foreign land.

    People have been making and flying kites for about 2,000 years. {#blank#}1{#/blank#}Some historians believe it the ancient Chinese may have started kite flying 2000 years ago. It is still a popular hobby in China, Japan and Korea and in other countries of the Far East where beautifully decorated appear in different colors.

    {#blank#}2{#/blank#}Simple kites are made by crossing two sticks and covering them with paper or cloth. Then you attach a string at the end. More expensive kites have frames made of fiberglass, plastic or aluminum. The name comes from a graceful bird called kite.

    {#blank#}3{#/blank#}A flat kite is the oldest and simplest type of kite.  It flies because air flows over and under the kite's wing. The pressure under the wing helps the kite lift into the air.

    {#blank#}4{#/blank#}Early scientists sent kites up into the air to measure temperature at different heights. In 1752, Benjamin Franklin used a kite to prove that lightning was a form of electricity. He attached a metal key to the string of a kite. When lightning hit the kite, electricity passed down the string and Franklin got an electric shock. It was a very dangerous experiment that you shouldn't copy.

    Kites were also used to develop airplanes. The Wright Brothers experimented with kites before they flew the first airplane. {#blank#}5{#/blank#} In World War I the Germans developed a large kite that could transport people to a submarine. Kites were also used to carry radio signals over long distances.

    Today most people fly kites as a hobby. Kite festivals are organized in many cities in all parts of the world.

A. Kites are made in many different sizes, colors and shapes.

B. flying kites is great fun and it is easy if you know some secrets.

C. Kites have also been used in experiments.

D. No one knows for sure who invented the kite.

E. In Japan families fly fish kites on Children's Day, May5th.

F. Stories of kites were brought to Europe till the end of the 13^th century.

G. In the past, kites were sometimes used to take pictures in wars.

    Film has properties that set it apart from painting, sculpture, novels and plays. It is also, in its most popular and powerful form, a story telling medium that shares many elements with the short story and the novel. And since film presents its stories in dramatic form, it has even more in common with the stage play: Both plays and movies act out or dramatize（使戏剧化）, show rather than tell, what happens.

    Unlike the novel, short story, or play, however, film is not handy（日语做的）to study; it cannot be effectively frozen on the printed page. The novel and short story are relatively easy to study because they are written to be read. The stage play is slightly more difficult to study because it is written to be performed. But plays are printed, and because they rely heavily on the spoken word, imaginative readers can bring mind at least a pale imitation of the experience they might have been watching a performance on stage. This cannot be said of the screenplay（电影剧本）, for a film depends greatly on visual（视觉的）and other non-visual elements that are not easily expressed in writing. The screenplay requires so much “filling in” by our imagination that we cannot really obtain the experience of a film by reading a screenplay, and reading a screenplay is worthwhile only if we have already seen the film. Thus, most screenplays are published not to read but rather to be remembered.

    Still, film should not be ignored because studying it requires extra effort. And the fact that we do not generally “read” films does not mean we should ignore the principles of literary of dramatic analysis when see a film. Literature and films do share many elements and communicate many things in similar ways. Perceptive（精辟的）film analysis rests on the principles used in literary analysis, and if we apply what we have learned in the study of literature to our analysis of films, we will be far ahead of those who do not. Therefore, before we turn to the unique elements of film, we need to look into the elements that film shares with any good story.

    Dividing film into its various elements for analysis is a somewhat artificial process, for the elements of any art form never exist in isolation. It is impossible, for example, to isolate plot（情节）from character. Events influence people, and people influence events; the two are always closely interwoven in any fictional（虚构的）, dramatic, or cinematic（电影的）work. Nevertheless, the analytical method uses such a fragmenting（碎片）technique for convenience. It does so with the assumption（假设）that we can study these elements in isolation without losing sight of their interdependence or their relationship to the whole.

    Public transport is declining in the rich world. To those who have to squeeze onto the number 25 bus in London, or the A train in New York, the change might not be noticeable. But public transport is becoming less busy in those places, and passenger numbers are flat or falling in almost every American city. That is despite healthy growth in urban populations and employment.

    Although transport agencies blame their unpopularity on things like road works and broken signals, it seems more likely that they are being outcompeted. App-based taxi services like Uber and Lyft are more comfortable and convenient than trains or buses. Cycling is nicer than it was, and rental bikes are more widely available. Cars are cheap to buy, thanks to cut-rate loans, and ever cheaper to run. Online shopping, home working and office-sharing mean more people can avoid travelling altogether.

    The competition is only likely to grow. More than one laboratory is developing new transport technologies and applications. Silicon Valley invented Uber and, more recently, apps that let people rent electric scooters(滑板车) and then abandon them on the pavement. China created sharing-bicycles and battery-powered "e-bikes", both of which are spreading.

    Transport agencies should accept the upstarts, and copy them. Cities tend either to ignore app-based services or to try to push them off the streets. That is understandable, given the rules-are-for-losers attitude of firms like Uber. But it is an error.

    It is doubtful that most people make hard distinctions between public and private transport. They just want to get somewhere, and there is a cost in time, money and comfort. An ideal system would let them move across a city for a single payment, transferring from trains to taxis to bicycles as needed. Building a platform to allow that is hard, and requires much sweet-talking of traditional networks as well as technology firms. It is probably the secret to keeping cities moving.