——Some students often drop litter carelessly in our school. What can we do?——We can _______ some signs to remind them not to do that again.
俄罗斯所处的纬度较高,其气候特征是
在809-47+334中,先算____法。
如图1,已知二次函数y=ax2+bx+c(a、b、c为常数,a≠0)的图象过点O(0,0)和点A(4,0),函数图象最低点M的纵坐标为﹣ 83 ,直线l的解析式为y=x.