地球上昼夜长短变化幅度最大的地区( )
-_________ weather it is! We can't go boating on the Xuanwu Lake.
-Don't worry. Let's go to the Science Museum instead.
若方程(m2﹣9)x2﹣(m﹣3)x﹣y=0是关于x,y的二元一次方程,则m的值为( )