A:f'(x0)>0
B:f'(x0)<0
C:f'(x0)=0
D:f'(x0)不存在
已知引力常量G和下列各组数据,能计算出地球质量的是( )
分解因式:ab﹣b=____
Wild animals are our friends. We shouldn't kill them food or clothing.