单项选择题 When an operator is trying to log off the system displays this message: you have running jobs?? What does this mean?（）

单项选择题 An application owner wants to grant write permission to all users for all the files and directories in the application directory. Which of the following is the correct command?（）

单项选择题 The operator needs to change the /test filesystem in the testvg volume group so that it mounts automatically following a system reboot. Which of the following commands is correct?（）