A:say
B:speak
C:talk
①5mL量筒②10mL量筒③20mL量筒④胶头滴管.
Molly ____ ____ to come to the airport at six that morning.
如图,抛物线y=﹣x2+2x+m+1交x轴于点A(a,0)和B(b,0),交y轴于点C,抛物线的顶点为D,下列三个判断中:
①当x>0时,y>0;
②若a=﹣1,则b=4;
③抛物线上有两点P(x1,y1)和Q(x2,y2),若x1<1<x2,且x1+x2>2,则y1>y2;正确的是( )
正方体ABCD﹣A1B1C1D1的棱长为2,则D1到平面A1BD的距离为( )