41. 如图,在正方体ABCD−A1B1C1D1ABCD-A_{1}B_{1}C_{1}D_{1}ABCD−A1B1C1D1中,点MMM,NNN分别是棱DD1DD_{1}DD1和线段BC1BC_{1}BC1上的动点,则满足与DD1DD_{1}DD1垂直的直线MN(MN(MN( )))