单项选择题 An operator needs to transfer several files in the same directory using ftp without being prompted. Which of the following ftp subcommands must be used?（）

单项选择题 What is the default configuration file used by the sendmail command?（）

单项选择题 An operator is asked to verify the exact location of the default JRE binary. The following commands were run: $ which java /usr/bin/java $ ls -l /usr/bin/java lrwxrwxrwx 1 root other 23 Jan 27 2006 /usr/bin/java -> ../jre1.5.0_06/bin/java Based on the command outputs above, what is the path to the java executable file?（）