David’s got a text message from his friend Sam．Can you understand it?

　　7,15　　20,15　　20,8,5　　16,1,18,11

　　This message was in code(密码，代码)．How many letters are there in the English alphabet?Twenty-six．So can you read it now?

　　David decided to use a different code in his answer to Sam．This time, he was putting A instead of B, B instead of C, and so on．His message to Sam shown on the right was very short．Can you understand?

　　Sam guessed David’s code, and he replied：ZESDQ RBGNNK．When David’s little sister saw the message, she felt puzzled．She couldn’t read it at all．But David was very happy that his sister couldn’t read his message!

　　Lots of people use codes to send secret messages．In a war, secrets are very important so soldiers often send each other messages in code．Nowadays, we can use computers to make and break difficult codes．Even before computers, people invented other machines to do this．

　　Here’s a famous machine that Germans used in the Second World War(1941－1945)．It’s called the Enigma Machine．The machines were very big, heavy and expensive．Every day they changed the codes automatically, and this made it almost impossible for anyone to break the codes．The person sending a message had one machine, and the person receiving the message had another．

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阅读下列短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。

　　This dog was born on Christmas Eve in 2002．He was different from other dogs because he was born with only two legs．The poor dog of course could not walk and even his mother Sarah did not want him．His first owner Michael Johnson also did not think that he could survive and he was thinking of killing him．But then, his present owner, Jude Stringfellow, met him and wanted to take care of him．She decided to teach and train this little dog to walk by himself．She called him “Faith”．

　　In the beginning, she put Faith on a surfboard(滑板)to let him feel the movement… Later she used peanut butter on a spoon as a lure(诱惑)and reward for him for standing up and jumping around．Even the other dog at home encouraged him to walk．Amazingly, after only six months, Faith learned to balance on his legs and jump to move forward．After further training in this snow, he could now walk like a person．

　　Faith loves to walk around now．Wherever he goes, he attracts people's attention．He is fast becoming famous on the international scene and has appeared on various newspapers and TV shows．A book named With a Little Faith is now being published about him．He was even considered to appear in one of Harry Potter movies．

　　Jude Stringfellow, his present owner, has stopped working and plans to take him around the world to tell people “that even without a perfect body, one can have a strong will(意志)”．

　　Faith is a good example of the strong will and wonder of life．In life there are always unpleasant things．So, in order to feel better, you just need to look at life from another direction．I hope this message will bring fresh new ways of thinking to everyone and that everyone will appreciate and be thankful for each beautiful day．

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