单项选择题 A user states that when the user copies files from ‘My Documents’ to a network share, the files are no longer available locally. Which of the following BEST describes the reason the files are no longer visible?（）

单项选择题 Bob, a technician, is troubleshooting a PC that intermittently does not power on. Which of the following tools would be the BEST choice to use to verify a possible cause? （）

单项选择题 A new floppy drive was just installed into a PC. The drive powers on at system boot but the status LED does not turn off during operation. Which of the following is MOST likely the issue?（）