单项选择题 A technician is dispatched to install additional RAM in a computer. The technician unplugs thesystem from the power source, and removes the cover of the PC. Which of the following shouldthe technician do NEXT?（）

单项选择题 A technician is dispatched to a location. While working, the technician’s cell phone rings. Which of the following actions should the technician take?（）

单项选择题 A technician has been asked to ensure a PC is supplied with power for a short time, during apower failure. The technician should install which of the following devices to ensure thisrequirement is easily met?（）