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#e88245e8-fd6e-4577-9736-1eba3d4837f2中等解答题空间中的平行立体几何

6. 如图,在正方体ABCDA1B1C1D1ABCD-A_{1}B_{1}C_{1}D_{1},对角线A1CA_{1}C与平面BDC1BDC_{1}交于点OOACACBDBD交于点MMEEABAB的中点,FFAA1AA_{1}的中点,
求证:(1)C1C_{1}OOMM三点共线
(2)EECCD1D_{1}FF四点共面
(3)CECED1FD_{1}FDADA三线共点.