单项选择题 Which of the following can cause a ribbon on an impact printer to tear?（）

单项选择题 A user is unable to print to the network printer. A print job appears in their print queue and cannotbe deleted. The user has the correct permissions to modify and delete print jobs. All other users are able to print to the network printer. Which of the following procedures should the technician try FIRST?（）

单项选择题 A laptop has a non-functioning keyboard. After the keyboard was replaced with a known good one, the technician finds that the keyboard still is not functioning. Which of the following steps should the technician take NEXT?（）