单项选择题 Which of the following is the MAXIMUM cable length for 802.3 Ethernet?（）

单项选择题 Which of the following connectors is commonly used on a shielded twisted pair cable?（）

单项选择题 A user reports that they walked away from their laptop for 30 minutes and when they came backthe screen was very dim. The user tried moving the mouse and increasing the brightness setting,but neither worked. Which of the following should the technician do FIRST?（）