问题 填空题

有一类加密类型常用于数据完整性检验和身份检验,例如计算机系统中的口令就是利用______算法加密的。

答案

参考答案:单向散列(或不可逆加密)

解析: 不可逆加密,又称为单向散列算法,其特征是加密过程不需要密钥,并且经过加密的数据无法被解密,只有同样的输入数据经过同样的不可逆加密算法才能得到相同的加密数据。例如计算机系统中的口令就是利用不可逆加密算法加密的。

阅读理解

阅读理解。

     Bamboo (竹子) is one of nature's (自然) most surprising plants. Many people call this plant a tree, but it

is a kind of grass.

     Like other kinds of grass, a bamboo plant may be cut very low to the ground, but it will grow back very

quickly. A Japanese scientist reported one bamboo plant which grew 1. 5 meters (4 feet) in 24 hours! Bamboo

grows almost everywhere in the world except Europe. There are more than 1, 000 kinds of bamboo.

     Not all bamboo looks the same. Some bamboo plants are very thin. They may only grow to be a few

centimeters wide while others may grow to more than 30 centimeters (1 foot) across. This plant also comes

in different colors, from yellow to black to green.

     Bamboo has been used to make many things such as hats and kitchen tools ( 厨房用具). Because it is

strong, bamboo is also used to build buildings.

     Many Asian countries have used bamboo for hundreds of years. They often use bamboo for buildings

and supporting (支撑) new buildings and bridges while they are being built.

      In Africa, poor farmers are taught how to find water using bamboo. These African countries need cheap

way to find water because they have no money, and their fields often die from no rain and no water. Bamboo

pipes ( 管子) help poor farmers bring water to their thirsty fields without spending a lot of money.

1. How is bamboo like grass?

A. It grows quickly.

B. It's wood.

C. it is easy to cut.

D. It is very thin.

2. Though you can see bamboo everywhere, it doesn't grow _____.

A. in China

B. in Europe

C. on mountains

D. in Africa

3. Why is bamboo used by African poor farmers? Because _____.

A. it is cheap

B. it has different colors

C. it is strong

D. it has been used by Asians

4. Bamboo pipes can _____.

A. make money

B. be trees

C. grow quickly

D. carry water

5. In Asia, bamboo has been used for _____.

A. a short time

B. many thousands of years

C. many hundreds of years

D. about 100 years

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