6.
如图所示,正方体\(ABCD\)\(-\)\(A\)\({\,\!}_{1}\)\(B\)\({\,\!}_{1}\) \(C\)\({\,\!}_{1}\)\(D\)\({\,\!}_{1}\)的棱长为\(a\),\(M\),\(N\)分别为\(A\)\({\,\!}_{1}\)\(B\)和\(AC\)上的点,\(A\)\({\,\!}_{1}\) \(M\)\(=\)\(AN\)\(= \dfrac{a}{3}\),则\(MN\)与平面\(BB\)\({\,\!}_{1}\) \(C\)\({\,\!}_{1}\) \(C\)的位置关系是