∵AB∥CD
∴∠BAC=∠DCF
∵AD‖CE
∴∠DAC=∠ECF
∵AD为∠BAC的平分线
∴∠BAD=∠DAC
∴∠DCE=∠DCF-∠ECF
=∠BAC-∠DAC
=∠BAD
=∠DAC
=∠ECF
∴CE为∠DCF的平分线.