证明：（1）在平面ABCD内，∵MH⊥AB，BC⊥AB，∴MH∥BC，∵MH⊄平面BCE，BC⊂平面BCE，∴MH∥平面BCE．∵MH∥BC，∴AMMC＝AHHB．∵AM=FN，AC=FB，∴MC=NB．∴AMMC＝FNNB．∴AHHB＝FNNB，∴NH∥AF∥BE．又∵NH⊄平面B...