问题 单项选择题

SET通过使用()来保证数据的一致性和完整性。

A.数字签名

B.公开密钥

C.对称密钥

D.私有密钥

答案

参考答案:A

阅读理解

根据短文内容,判断正(T)误(F)。

     1970 was World Conservation (保护) Year. The United Nations wanted everyone to know that the world

is in danger. They hoped that governments (政府) would act quickly to conserve nature (保护自然). Here is

one example of the problem. At one time there were 1,300 different plants, trees and flowers in Holland but

now only 866 remain. The others have been destroyed by modern man and his technology. We are changing

the earth, the air, the water and everything that grows and lives. We can't live without these things. If things

go like this, we shall destroy ourselves.

     What will happen in the future? Perhaps it is more important to ask, "What must we do now?" The people

who will be living in the world of tomorrow are the young of today. A lot of them know conservation is

necessary. Many are helping to save our world. They plant trees, build bridges across rivers in forests, and

so on. In a small town in the United States, a large number of girls cleaned the banks of 11 kilometers of their

river. Young people may hear about conservation through a record called "No one is going to change our

world." It was made by the Beatles, Cliff Richard and other singers. The money from it will help to conserve

animals.

( )1. The United Nations wanted everybody to know that the world is in danger.

( )2. There are fewer plants, trees and flowers in Holland because many kinds of plants, trees and flowers

            can't grow there any more.

( )3. The most important thing for us to do is to clean the banks of our rivers.

(     )4. "No one is going to change our world" is a name of a song.

( )5. From this passage we know that we must conserve nature.

多项选择题