请任意写出变流系统中的5种故障名称。
A system administrator boots a server in normal mode, the boot process displays and LED 551 and stops. LED 551 indicates the root volume group is being varied on. All of the following are probable causes of the problem EXCEPT:（） ["The bosboot command failed to complete.","The JFS log device is corrupted.","The initttab file is corrupted.","The \/dev entries or \/etc files are missing."]
以下（）操作不是在拆除开孔机前完成的。 ["A、提起筒刀 ","B、提起塞柄 ","C、关闭夹板阀 ","D、卸下筒刀"]
104型制动机的常用制动波速最大约为（）。 ["140m／s","170m／s","180m／s","190m／"]
When dividing an existing Class B network into 2 subnets of 32，766 hosts each， which of the following subnet masks should be used？（） ["128.0.0.0","255.128.0.0","255.254.0.0","255.255.128.0"]
隐性采访
