关于力、力和运用的关系,下列说法正确的是 ()
如图,△ABC中,∠ABC和∠ACB的平分线交于点F,过点F作DE∥BC交AB于点D,交AC于点E,那么下列结论:①△BDF和△CEF都是等腰三角形;②∠DFB=∠EFC;③△ADE的周长等于AB与AC的和;④BF=CF.其中正确的是( )
--There ______ many trees at the foot of the mountain.--But now they are slowly disappearing because of human activities.