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 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 For example, the first letters of "My elephant eats too many eels" Spell out the hidden message "Meet me."
38 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 For example "bridge" might stand for "meet" and "out" might stand for "me." The message "bridge out" would actually mean "Meet me." 40 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. |
阅读下面短文，掌握其大意，然后从方框中选出能填入文中空白处的最合适的单词，并将该单词填写在答题卡对应题号的横线上，注意单词的适当形式。
| broadcast buy dream famous however joke make exciting organize suggest |
Susan and I loved jazz and we of becoming musicians. We decided to form a band so that we could
some extra money by playing and singing in a pub(酒吧). The regulars(常客) there were very kind to us. They
we go to record our songs in a studio. We wondered if they were playing a
on us as they were often very humorous to each other.
, to our great surprise, everything was
and we made our record. Imagine our excitement when we heard it
on the radio for the first time! It was almost as
as later when we became millionaires. Now whenever we go to the pub, we play our songs and
drinks for the regulars. Although we are
, we still like to play in the familiar places.
阅读下面短文，根据以下要求：1）括号内汉语提示；2）该词首字母提示；3）上下文语境提示, 在每个空格内填空入一个适当的英语单词使短文通顺，所填单词要求拼写正确、形式符合英语表达习惯。
Dear Sirs,
My name is Wang Qing. I’m a boy of 18 years old. Right now I’m studying Anxi No.1 Senior High School, Fujian, China. I hope
to go to your university for further study after (毕业).
I’ve aachieved good scores in all my subjects, especially in
physics and I have (赢得)several prizes in the physics competitions.
I am really kon English and my listening, reading and writing in
English are excellent, too. I do (运动) in my spare time. I’m a
member of some clubs in my school, as the English Club and
the Physics Learning Group. I hope to sphysics in your university
because I have been very interested in it I was in the junior middle
school. I would be very gif I could get the chance!
With best wishes.
Yours,
Wang Qing
The aof scientists towards the rise is completely different. On the one hand, Dr Foster thinks that the trend which increases the temperature by 5 degrees would be a
(大灾难). On the other hand, George Hambley, who is o
to this view, predicts that any warming will be
(温和的) with few bad environmental c
.
James’ grandfather wrote to help James qsmoking. James’ grandfather once became a
to cigarettes in three ways. His body was a
to having nicotine. He began to do it
(自动地) and became
(心理上) interested. But he finally managed to stop when realizing the harmful effects of it.
The air we breathe is freely available, without we could not survive more than a few minutes. For the most part, air is available to everyone, and everyone needs it. Some people use the air to sustain them while
(sit) around and feel sorry for themselves.
breathe in the air and use the energy it provides to make
magnificent life. Opportunity is
the same way; it is everywhere. It is so freely available that we take it for granted. Yet opportunity alone is not enough to create success; it must
(seize) and acted upon in order to have value.
many people are so anxious to “get in” on a “ground floor opportunity”, as if the opportunity will do all the work that’s
(possible). Just as you need air to breathe, you need opportunity to succeed. However, it takes more than just breathing in the fresh air of opportunity. You must make use of it. That’s not up to the opportunity; that’s up to you.
doesn’t matter what “floor” the opportunity is on, but
matters is what you do with it.