If you and your friends wish to share a secret, you can write it in code, and no one else will be able to read it. Codes are one way of writing in secrets. Ciphers are another. In the code each word is written as a secret code or word number. In a cipher each letter is changed.
Codes and ciphers have played an important role in the history of the word. Julius Caesar, the Roman ruler who defeated almost all the countries in Europe about 2000years ago, used a cipher when he sent secret messages to his troops. During American Revolution, George Washingtons spies used a kind of code to send him information about the enemy before his military(军事的) action. In World War 2,the American broke, or figured out, Japans most important navy codes and got enough information to destroy a powerful Japanese fleet(舰队)。
Storekeepers use codes to mark their goods. The codes show how much was paid for the goods or when they were added to the stock. Businessman use codes to hide plans from their business enemies. Sometimes personal letters or diaries are written in code. Many people enjoy figuring out codes and ciphers simply as a hobby.
In the 16th century, codes and ciphers were very popular among scientists. They wrote messages to each other in code so that no one else would learn their secrets. Geronimo Gardano, an Italian astrologer(星相家),mathematician, and doctor, invented the trellis ciphers. He took two sheets of paper and cut exactly the same holes in each one. Then he sent one sheet, which he called a trellis, to a friend and kept the other for himself. Whenever he wanted to write a message, he put his trellis, over the clean sheet of paper and wrote the secret message through the holes. Then he removed the trellis and filed the rest of the paper with words that would make sense. When his friends received it, He put his trellis over the writing and read the secret message.
Title 1.
Keys:
1. Codes and ciphers 2.In business 3. through the holes
4. meaningful information/messages 5. Purposes/Aims
6. send secret messages/information 7. informed/know/learn/aware/conscious
8.To hide plans/information/messages 9.keep secrets 10. Defeating
小学六年英语词组归纳
小学趣味英语单词G的学习
小学英语分类词汇表 12
英语词汇 英文构词词根表 5
英语词汇 英语单词词源100讲 9
英语词汇 天气词汇中英文对照表
儿童英语单词学习 文件用品
小学趣味英语单词J的学习
小学英语分类词汇表 15
英语词汇 品牌中的英语含义
英语词汇 一些常见海鲜菜的说法
英语词汇 600句中文短语英文表达1
小学英语分类词汇表 18
喜欢与厌恶表达用语小结
英语词汇 英语单词词源100讲 5
常见的英语同义词50组(2)
小学英语分类词汇表 19
英语词汇 英语单词词源100讲 3
小学英语分类词汇表 16
小学英语分类词汇表 9
小学趣味英语单词C的学习
英语词汇 世界各国货币名称
小学趣味英语单词H的学习
小学趣味英语单词E的学习
英语词汇 音乐常用术语
小学英语分类词汇表 2
认字,是牢固记字之本, 好方法让记英语单词痛彻不忘
告别表达方法小结
英语词汇 中英文天气预报对照表
英语中只能用复数形式的名词
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |