ER模型可以转换成关系模型。当两个实体间联系是M:N联系时，它通常可转换成(27)个关系模式。

(59)

(57)

Programmers test a program by running it to ensure that the(74)are correct and that the program produces the desired outcome. If errors do occur, the programmer must make the appropriate change and recheck the program until it produces the correct results. This(75)is called testing and debugging.

Computer hardware engineers research, design, develop, and test computer hardware and supervise its manufacture and(72). Hardware refers to computer(73), circuit boards, computer systems, and related equipment such as keyboards, modems, and printers.

(55)

The major goal of USB was to define an external expansion bus which makes adding(70)to a PC as easy as hooking up a telephone to a wall-jack. USB 2.0 is an evolution of the USB 1.1(71), providing a higher performance interface.

Like　personal　computers,　most　workstations　are(72)computers

The　term　data　is　often　used　to　distinguish()machine-readable　information　from　textual　human-readable　information.

(50)

The　major　technical　areas　of　computer　security　are　usually　represented　by　the　initials　CIA:(66),　integrity,　and　authentication　or　availability.