单项选择题 When testing a CAT5 cable, the technician notices that pin A is open. However, the cable stillworks fine. Which of the following describes how this is possible?（）

单项选择题 Which of the following allows a WAP to be installed in a location where there are no power outletsavailable?（）

单项选择题 A technician needs to add network capacity. However, when plugging a second switch into the first switch, there is no link light. Which of the following is the cause of this situation?（）