多项选择题
A user is reporting that a PC will suddenly shut down without warning. The PC boots up with no problems, but after using the PC for a short time, the PC turns off. Which of the following components should the technician check?（） (Select TWO).
A. CPU fan B. RAM C. Hard drive D. Power supply E. Video card
单项选择题 Which of the following is the default location for temp files in Windows 7?（）
单项选择题 Which of the following commands is used to delete an empty directory?（）
单项选择题 Which of the following is the default SMTP port?（）
