2016年全国卷1

第二节(共1小题，每小题10分，满分10分)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.(36)　D　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.(37)　E　For example，the first letters of"My elephant eats too many eels"Spell out the hidden message"Meet me."

(38)　G　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.(39)　F　For example，"bridge"might stand for"meet"and"out"might stand for"me."The message"bridge out"would actually mean"Meet me."(40)　A　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.

答案解析：

36. D 这一句的前后文都在谈论密码的制造和破解，所以选项D "As long as there have been codes, people have tried to break them."(只要有密码，人们就会尝试破解它们。)与上下文最为吻合，说明了密码制造和破解的历史悠久。

37. E 接下来的例子说明了如何通过每个单词的首字母来隐藏信息，所以选项E "You can hide a message by having the first letters of each word spell it out."(你可以通过让每个单词的首字母拼出隐藏信息来隐藏信息。)与例子内容相匹配。

38. G 这一段讲述了另一种隐藏信息的方法，即用符号代表字母表中的特定字母，所以选项G "Another way to hide a message is to use symbols to stand for specific letters of the alphabet."(另一种隐藏信息的方法是使用符号代表字母表中的特定字母。)与段落内容相符。

39. F 这一段讲述了代码本的使用，即用代码本中的单词代表其他单词，所以选项F "With a code book, you might write down words that would stand for other words."(有了代码本，你可能会写下代表其他单词的单词。)与段落内容相符。

40. A 这一句是对代码本安全性的讨论，所以选项A "It is very hard to break a code without the code book."(没有代码本，破解代码是非常困难的。)与上下文讨论的代码本保密性困难相匹配。