2. A backup program makes a copy of files you select.（ ） A. 错误 B. 正确 ...

17. A （ ） port is an interface that connects devices by transferring more than one bit at a time. A. serial B. parallel C. USB D. none of the above ...

12. The first computers used （ ） for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. A. vacuum tubes B. transistors C. integrated circuits D. microprocessors ...

7. （ ） are output devices that print characters, symbols, and graphics on a physical medium such as paper and a transparency file. A. Flat panel monitors B. Printers C. Keyboards D. Pointing device ...

2. （ ） performs arithmetic, comparison, and logic operations. It is one part of the CPU. A. RAM B. ROM C. CPU D. ALU ...

7. The ENIAC used thousands of vacuum tubes,which took up a lot of space and gave off a great deal of heat just like light bulbs do.（ ） A. 错误 B. 正确 ...

2. The microprocessor led to the invention of personal computers,or microcomputers.（ ） A. 错误 B. 正确 ...

10. 可导的奇函数的导数是奇函数 A. 错误 B. 正确 ...

8. 波阻抗是一个比例常数，其数值只与导线单位长度的电感和电容有关，与线路长度无关。 A. 错误 B. 正确 ...

3. 局部放电会逐渐腐蚀、损坏绝缘材料，使放电区域不断扩大，最终导致整个绝缘体击穿。 A. 错误 B. 正确 ...