A library was built in honour of the great scientist.
→A library was built ____ ____ ____ the great scientist.
在圆x2+y2=16上任取一点P,过点P作x轴的垂线段PD,D为垂足,当点P在圆上运动时,线段PD的中点M的轨迹方程是( )
下列四边形中,对角线不可能相等的是( )