Why not ____ help when you were in trouble?
A:you ask for
B:ask for
C:asking for
D:to ask
如图所示的几何体是由六个相同的小正方体组合而成的,它的俯视图是( )
读经纬网图回答:从A到B再到C,方向是( )
标着甲“220V,40W”和乙“36V,40W”的两只电灯,则电灯乙的额定功率为____ ;若两灯都能正常发光时,比较它们的亮度是____ .