A:why; because
B:why; whether
C:that; that
D:how; that
已知集合A={x|y=2x-x2},B={y|y=2x,x>0},R是实数集,则(∁RB)∩A= ____.
Only after she had arrived home _______ her appointment with the doctor.
10个边长为2厘米的小正方体堆成如图的形状,求它的表面积。
下列有关电流、电压、电阻的分析正确的是( )