Question

【题目】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. 【1】Code breaking never lags（落后）far behind code making. The science of creating and reading coded messages is called cryptography.

There are three main types of cryptography. 【2】 For example, the first letters of “My elephant eats too many eels” spell out the hidden message “Meet me.”

【3】 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 “135520135.”

A code uses symbols to replace words, phrases, or sentences. To read the message of a real code, you must have a code book. 【4】 For example, “bridge” might stand for “meet” and “out” might stand for “me.” The message “Bridge out” would actually mean “Meet me.” 【5】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.

Answer 1

【答案】

【1】D

【2】E

【3】G

【4】F

【5】A

【解析】

试题分析：文章介绍了密码的重要性、密码的设置方式、密码书的作用。

【1】D考查对上下文的理解和推理判断能力。上句讲人们使用密码已经几千年了，下句讲密码破译工作。空白处和密码破译有关，D项内容符合语境，连接上下文。故选D.

【2】E考查对上下文的理解和推理判断能力。后面的例子是来证明人们设置密码时往往会利用一些单词的第一个字母作为密码，E项符合此内容，故选E.

【3】G考查对上下文的理解和推理判断能力。根据下文的解释内容可知介绍了密码设置的又一种方法，G项符合此意，故选G.

【4】F考查对上下文的理解和推理判断能力。根据下文的例子及上句中的a code book可以判断该句是介绍密码书的使用，F项符合此意，承上启下。故选F.

【5】A考查对上下文的理解和推理判断能力。上文介绍密码书的重要作用，A项：没有密码书很难破译，总结上文。故选A.