python笨办法,但覆盖全面:
思路:mystr.find(str) # 返回str在mystr中的索引值,-1表示str不在mystr中

#1定义执行函数
def execute(cmd):
    if len(cmd.split())==1:#若只有一个关键字
        if 'reset'.find(cmd)==0 :
            return 'reset what'
        else:
            return 'unknown command'
    elif len(cmd.split())==2:#若有两个关键字 
        CMD=cmd.split()
        if 'reset'.find(CMD[0])==0 and 'board'.find(CMD[1])==0 and 'backplane'.find(CMD[1])==-1:
            return 'board fault'
        elif 'board'.find(CMD[0])==0 and 'add'.find(CMD[1])==0 and 'abort'.find(CMD[1])==-1:
            return 'where to add'
        elif 'board'.find(CMD[0])==0 and 'delete'.find(CMD[1])==0:    
            return 'no board at all'
        elif 'reboot'.find(CMD[0])==0 and 'backplane'.find(CMD[1])==0 and 'board'.find(CMD[1])==-1:       
            return 'impossible'
        elif 'backplane'.find(CMD[0])==0 and 'abort'.find(CMD[1])==0 and 'add'.find(CMD[1])==-1:   
            return 'install first'
        else:
            return 'unknown command'
    else:#若超过两个关键字
        return 'unknown command'

#2调用已定义的执行函数
while True:
    try:
        cmd=input()
        print(execute(cmd))
    except:
        break