如图,在平面直角坐标系中,矩形OABC,OA=3,OC=6,将△ABC沿对角线AC翻折,使点B落在点B′处,AB′与y轴交于点D,则点D的坐标为 ____.
下列属于非特异性免疫的是( )
decide different little through healthy
It is difficult for us to imagine_____ life was like for slaves in the ancient world.
一个等腰三角形的一边长是5cm,周长是20cm,求其他两边的长.