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.

    Most people agree that honesty is a good thing. But does Mother Nature agree? Animals can't talk, but can they lie in other ways? Can they lie with their bodies and behavior? Animal experts may not call it lying, but they do agree that many animals, from birds to chimpanzees, behave dishonestly to fool other animals. Why? Dishonesty often helps them survive.

    Many kinds of birds are very successful at fooling other animals. For example, a bird called the plover sometimes pretends to be hurt in order to protect its young. When a predator（猎食动物）gets close to its nest, the plover leads the predator away from the nest. How? It pretends to have a broken wing. The predator follows the "hurt" adult, leaving the baby birds safe in the nest.

    Another kind of bird, the scrub jay, buries its food so it always has something to eat. Scrub jays are also thieves. They watch where others bury their food and steal it. But clever scrub jays seem to know when a thief is watching them. So they go back later, unbury the food, and bury it again somewhere else.

    Birds called cuckoos have found a way to have babies without doing much work. How? They don't make nests. Instead, they get into other birds' nests secretly. Then they lay their eggs and fly away. When the baby birds come out, their adoptive parents feed them.

    Chimpanzees, or chimps, can also be sneaky. After a fight, the losing chimp will give its hand to the other. When the winning chimp puts out its hand, too, the chimps are friendly again. But an animal expert once saw a losing chimp take the winner's hand and start fighting again.

    Chimps are sneaky in other ways, too. When chimps find food that they love, such as bananas, it is natural for them to cry out. Then other chimps come running. But some clever chimps learn to cry very softly when they find food. That way, other chimps don't hear them,  and they don't need to share their food.

    As children, many of us learn the saying "You can't fool Mother Nature." But maybe you can't trust her, either.

Five years ago, when I taught art at a school in Seattle, I used Tinkertoys as a test at the beginning of a term to find out something about my students. I put a small set of Tinkertoys in front of each student, and said: "Make something out of the Tinkertoys. You have 45 minutes today - and 45minutes each day for the rest of the week."

    A few students hesitated to start. They waited to see the rest of the class would do. Several others checked the instructions and made something according to one of the model plans provided. Another group built something out of their own imaginations.

    Once I had a boy who worked experimentally with Tinkertoys in his free time. His constructions filled a shelf in the art classroom and a good part of his bedroom at home. I was delighted at the presence of such a student. Here was an exceptionally creative mind at work. His presence meant that I had an unexpected teaching assistant in class whose creativity would infect(感染) other students.

Encouraging this kind of thinking has a downside. I ran the risk of losing those students who had a different style of thinking. Without fail one would declare, "But I'm just not creative."

"Do you dream at night when you're asleep?"

"Oh, sure."

"So tell me one of your most interesting dreams." The student would tell something wildly imaginative. Flying in the sky or in a time machine or growing three heads. "That's pretty creative. Who does that for you?"

"Nobody. I do it."

"Really-at night, when you're asleep?"

"Sure."

"Try doing it in the daytime, in class, okay?"

    The British economy is showing the greatest signs of stress since the Eurozone crisis and fears of a double-dip recession（衰退）six years ago, as worrying reports show the steepest fall in manufacturing（制造业）output and the greatest degrees of pessimism among employers since 2012. Concerns over Brexit（英国脱欧）and a slowdown for high street spending are among the major factors contributing towards 2018 being the worst time in six years for British firms planning to take on new staff, according to a closely watched survey conducted by the employment firm ManpowerGroup.

    Watched by the Bank of England and the government for early warnings of hiring increases or downturns, the quarterly poll（季度民意调查）of about 2,000 major employers from nine different industry sectors across the UK found a net balance of only 4% planning to hire more staff rather than cutting back.

    The weakest outlook from the survey was reserved for the banking and finance industry, which recorded the worst outlook since the depths of the financial crisis almost a decade ago, suggesting job cuts may be on the way over the summer.

    The barometer（晴雨表）of hiring sentiment comes as Britain's factories unexpectedly recorded the sharpest drop in output for more than five years in April. Pointing to fewer orders for steel used in infrastructure（基础设施）projects and a wider slowdown in demand for British goods at home and abroad, the Office for National Statistics said manufacturing output fell by 1.4% in April from the previous month. Economists had forecast modest growth of 0.3%.

    Although the situation does not appear to be as severe this year, forecasts issued by the National Institute of Economic and Social Research on Monday suggest the UK has done little to bounce back from heavy snowfall earlier in 2018. Putting the growth rate for GDP at only 0.2% in the three-month period to May, up from 0.1% in the same period ending in April, Niesr's head of UK macroeconomic forecasting, Amit Kara, said: “Economic growth has slowed materially since the start of this year and it continues to remain weak.”

    Teen Art Show

    Do you want to see your artwork displayed alongside other teens' artwork? Don't miss your opportunity! Showcase your paintings, sculptures, photographs and other artworks at the Environmental Educational Center. The show will provide an opportunity for artists to network, provide feedback and become a resource for others.

    Activity fee: $25

    Night Fishing

    Escape the night and join us as we fish at Desert Breeze Park. No experience needed. We will provide the fishing poles, transportation, the bait, help you catch a fish and best of all, teens 14 years and under do not require a license to fish.

    Location: Desert Breeze Park

    Activity fee: $22

    Overnight Snow Trip

    Join the City of Chandler in an exciting new trip! We will travel up to Camp Tontozona and enjoy great food and a campfire in the early evening. Snow play will be the highlight as we explore the snow-filled meadows(草地) of Woods Canyon Lake and sled down small hills in the area. You will be responsible for your own ski/snowboard equipment.

    Location: Camp Tontozona

    Activity fee: $30

    Paintballing

    Come out and play paintball with all your friends! Join the City of Chandler as we go to Tempe Indoor Paintball. This is a great way to join in the fun of playing paintball for a low, low cost. All equipment is included. Please wear old clothes because clothes can get dirty easily!

    Location: Tempe Paintball

    Activity fee: $28

    I grew up on a farm outside Port Clinton, Ohio. I was the youngest son, with four brothers and four sisters, plus a girl my relatives took in when she was in sixth grade and was raised along with us.

    By the late 60s, most of us were married and had families of our own. One day, while we were visiting my parents in late summer or early fall, Dad mentioned he'd always wanted a Crimson King maple tree for the yard. Mom agreed that they were pretty.

    Like many parents, mine were hard to shop for, so I figured this was a great opportunity to get them something they'd appreciate. I checked the price at work and decided it was a bit more than I could afford but all of my brothers and sisters agreed to help.

    In northern Ohio, people don't plant maple trees at Christmas, so we decided to surprise Mom and Dad with a special Christmas in October before the ground froze. We asked my aunt if she'd help us with the trick, and she called my parents in advance to say she was coming for a Sunday visit. Then my sisters and sisters-in-law went into action, planning a big holiday turkey dinner.

    On the chosen Sunday, we all met at my house and loaded the trees in a pickup truck. I dressed up as Santa Claus, though at the time I weighed about 140, so all the padding(填料) in the world couldn't make me look like St. Nick. Then off we went, nine or ten cars loaded with people and food, plus the pickup truck.

    When the truck arrived at my parents' house, Dad came out of the back door, convinced something was wrong. He and Mom were amazed when we told them why we were there.

    When Christmas rolled around, of course, we couldn't go to our parents' house empty-handed, so Mom and Dad got double presents that year. Almost half a century later, I still drive by the old farm and smile when I see those big, handsome trees.