• 2022-06-30
    下列变量组是一个闭回路
    ( )
    A: {x21,x23,x13,x12,x32,x34,x44,x41}
    B: {x11,x12,x23,x34,x41,x13}
    C: {x12,x32,x33,x23,x21,x11}
    D: {x12,x22,x32,x33,x23,x21}