直线kx-y+1-3k=0,当k变化时,所有直线恒过定点_____________.
(3,1)
直线可以为y-1=k(x-3),∴过定点(3,1).
According to this passage, the status of the aged is lowered by their ______.
A．forced retirement
B．inferior housing
C．longer life span
D．fixed incomes
化学危险品事故应急救援的基本任务是什么？
