抛物线y=x2-4的顶点坐标是( )
A.(2,0)
B.(-2,0)
C.(1,-3)
D.(0,-4)
抛物线y=x2-4的顶点坐标为(0,-4).
故选D.
What would you like to drink ? [ ]
A. Two breads
B. A bread
C. Two pieces of bread .
()的高低直接影响凿岩机的冲击功、冲击频率和轴推力。