[单选题]Symmetric, or private-key, encryption is based on a secret key that is shared by both communcating parties. The （ ） party uses the secret key as part of the mathematical operation to encrypt （ ） text to cipher text. The receiving party uses the same secret key to decrypt the cipher text to plain text. Asymmetric, or public-key, encryption uses two different keys for each user: one is a （ ） key known only to this one user; the other is a corresponding public key, which is accessible to anyone. The private and public keys are mathematically related by the encryption algorithm. One key ia used for encyption and the other for decryption, depending on the nature of the communication service being implemented. In addition, public key encryption technoligies allow digital （ ） to be placed on messages. A digital signature uses the sender's private key to encrypt some portion of the message. When the message is received, the receiver uses the sender's （_______） key tp decipher the digital signature to verify the sender's identity. 横线处应选（ ）。
A.plain
B.cipher
C.public
D.private

[单选题]Symmetric, or private-key, encryption is based on a secret key that is shared by both communcating parties. The （ ） party uses the secret key as part of the mathematical operation to encrypt （ ） text to cipher text. The receiving party uses the same secret key to decrypt the cipher text to plain text. Asymmetric, or public-key, encryption uses two different keys for each user: one is a （_____） key known only to this one user; the other is a corresponding public key, which is accessible to anyone. The private and public keys are mathematically related by the encryption algorithm. One key ia used for encyption and the other for decryption, depending on the nature of the communication service being implemented. In addition, public key encryption technoligies allow digital （ ） to be placed on messages. A digital signature uses the sender's private key to encrypt some portion of the message. When the message is received, the receiver uses the sender's （ ） key tp decipher the digital signature to verify the sender's identity. 横线处应选（ ）。
A.plain
B.cipher
C.public
D.private

[单选题]Base64是网络上最常见的用于传输8Bit字节码的编码方式之一，Base64就是一种基于64个可打印字符来表示二进制数据的方法。电子邮件系统中使用base64编码的主要目的是
A.将二进制码转换成ASCII码
B.加密传输的邮件
C.压缩传输的邮件
D.提高邮件的传输速度

[单选题]10Base-5型LAN的运行速度和支持的粗缆最大长度是（ ）。
A.10Mbps，lOOm
B.10Mbps，200m
C.10Mbps，500m
D.16Mbps，500m

[不定项选择题]共用题干 Save Pandas
With the Switzerland-based World Wildlife Fund(WW F),China is making a concerted and dedicated effort to save the endangered pandas.The results,officials here in Chengdu indicate,are mixed but encouraging.
A clear disappointment is the failure to breed pandas in captivity,necessary if their decreasing numbers are to be replaced.Another failure has been the incapability to find a natural,readily available food to replace the arrow bamboo. Despite these failures,success has come on two fronts.One achievement has been the physical rescue effort.Some pandas have been kept alive by salting（空投）the mountains with tons of cooked meat , which pandas will eat as a substitute for bamboo,and by the planting of new bamboo in isolated areas.Animals in some Sichuan areas have been rescued by local peasants and given emergency treatment by animal doctors.
A second achievement is a massive fund-raising effort.Publicity about the pandas plight has resulted in a new$100,000 emergency allocation by the WWF and independent fund drives both in China and abroad.
In spite of this support,there have been conflicts in the panda relief program.One important problem is the difficulty Peking is having balancing the recommendations of environmentalists with China's ambitious goal of agricultural and industrial modernization.
Wolong is but one example of this difficulty.This 494,000-acre preserve was declared a protected area in 1975.Yet 1,800 people,mostly Tibetans,still live in the preserve,logging trucks still roll down the narrow mountain roads,and blasting work still goes on at the site of a new 160,000-kilowatt hydroelectric plant just six miles away.
This all means that the pandas'fight for survival will not be an easy one,even with the concerted effort of man.For in the end,even if they can survive the dangers of the wild,they must still contend with man himseff. The tone of the author's conclusion concerning pandas'survival is______.
A.worried
B.optimistic
C.angry
D.impersonal

[单选题]100Base-TX 采用的传输介质是（）
A.双绞线
B.光纤
C.无线电波
D.同轴电缆

[单选题]快速以太网标准100Base-TX规定的传输介质是
A.2类UTP
B.3类UTP
C.5类UTP
D.光纤

[单选题]1000Base-LX使用的传输介质是（ ）。
A.UTP
B.STP
C.同轴电缆
D.光纤