多项选择题 Which connections allow the use of full-duplex Ethernet?（）

单项选择题 What is the purpose of pressing the Ctrl+Break keys during the router password recover procedure?（）

多项选择题 Five minutes after issuing the show running-config command, a technician enters the command again and notices that several access list statements have been altered. Because of this, the technician believes that the router is being configured by an unknown person through Telnet. Before changing the router passwords, the technician would like to discover if anyone is connected to the router by Telnet and stop them from making further changes. Which commands will accomplish these options?（）