单项选择题 A technician plugs a USB device into the computer. The system tray displays a message that reports the device is installed, but may not work properly. Which of the following is the MOST likely cause of the message?（）

不定项选择 A customer reports that a networked printer is not printing documents. The technician successfullypings the printer’s IP address. Which of the following could be the problem? (Select TWO).（）

单项选择题 Which of the following describes a computer in which the HDD LED is lit, but the mouse does notrespond and the computer is unresponsive?（）