Question

【题目】 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?

A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21

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?

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

A

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.

【1】Sam asked David to go to the ________.

A.parkB.houseC.museumD.zoo

【2】Sam told David to meet him

A.before breakfastB.after schoolC.after dinnerD.before school

【3】Codes are used to keep something_________.

A.newB.oldC.secretD.known

【4】People will never know the meaning if they can’t _______ the code.

A.breakB.makeC.changeD.write

【5】The best title of this passage is _______.

A.English LettersB.CodesC.MessagesD.Machines

Answer 1

【答案】

【1】A

【2】B

【3】C

【4】A

【5】B

【解析】

本文是一篇说明文，由大卫和萨姆之间互传密码信息引入，介绍了人们使用密码的历史、背景等。

【1】推理判断题。根据This message was in code. How many letters are there in the English alphabet?可知该密码用26个英文字母对应的数字来构成，萨姆的数字密码对应成相应顺序的字母连起来意为go to the park，故选A。

【2】推理判断题。根据This time, he was putting A instead of B, B instead of C, and so on，可知回复的信息所用密码每个字母都往前推了一位，复位则要往后推回来，大卫的密码复位后是after school，故选B。

【3】细节理解题。根据Lots of people use codes to send secret messages，可知是为了保守秘密，故选C。

【4】细节理解题。根据Every day they changed the codes automatically, and this made it almost impossible for anyone to break the codes，可知不破解密码就不能知道它的意思，故选A。

【5】最佳标题。通读全文，可知文章主要由大卫和萨姆之间互传密码信息引入，介绍了有关密码的事情，故选B。