A:What do you want
B:What is it like
C:What are you going to
D:What does it look like
家兔是植食性动物,其区别于狼、豹等肉食性动物的最大特点是( )
如图,在Rt△ABC中,∠ACB=90°,AC=3,BC=4,过点B作射线BB1∥AC.动点D从点A出发沿射线AC方向以每秒5个单位的速度运动,同时动点E从点C沿射线AC方向以每秒3个单位的速度运动.过点D作DH⊥AB于H,过点E作EF⊥AC交射线BB1于F,G是EF中点,连接DG.设点D运动的时间为t秒.
当t为何值时,AD=AB,并求出此时DE的长度;