18.如图,在正方体ABCD−A1B1C1D1ABCD-A_{1}B_{1}C_{1}D_{1}ABCD−A1B1C1D1中,FFF为线段BC1BC_{1}BC1的中点,EEE为线段A1C1A_{1}C_{1}A1C1上的动点,下列四个结论中,错误的是((( )))