单选题 In ( ),the only element that can be deleted or removed is the one that was inserted most recently.

单选题 Most ( )measure involve data encryption and password.

单选题 The( ) in E-mail message has affected almost every computer around the world and has cause the damage of up to US$1 billion in North America.

单选题 A ( )consists of the symbols, characters, and usage rules that permit people to communicate with computer.

单选题 Insufficient ( )can cause a processor to work at 50% or even more below its performance potential.

单选题 One of the basic rules of computer security is change your ( )regularly.

单选题 ( )software, also called end-user program, includes data base programs ,word processors, spread sheets etc.

单选题 A( )is a function unit that interprets and carries out instructions.