The baby stops _______ as soon as he ______ his mother coming into the room.
A:to cry, sees
B:crying, will see
C:crying, sees
D:to cry, will see
如图所示,由于地球的自转,地球表面上P、Q两物体均绕地球自转轴做匀速圆周运动.
对于P、Q两物体的运动,下列说法正确的是( )
方程x(x-2)=0的根是( )