由题知S△ABD=1/2S△ABC,则S△AEB=1/2S△ABD=1/4S△ABC.S△BFC=1/4ABC.又由S△ADC=1/2S△ABC,可得S△AEC=1/2S△ADC=1/4S△ABC.
所以S△BEF=S△ABC-S△AEB-S△BFC-S△AEC=4-(1/4+1/4+1/4)4=1