单项选择题
A.showmount -e hostname
B.showmount -d hostname
C.showmount -a hostname
D.showmount
单项选择题 NFSisexperiencingnameserviceresolutiondifficulties.WhichcommandreportstheLEASTusefulinformationintrouble-shootingthisproblem？（）
单项选择题 Toenableattyporttobeusedforacusessionwhatmustbedonetothesystem？（）
单项选择题 Which of the following commands should be used to open a tty port configured in the /etc/uucp/Devices file as： Direct tty2 - 9600 direct in debug mode， ignoring modem control signal data carrier detect （DCD）？（）