A:4
B:6
C:65
D:0
The population of China is __________ than that of _________ country in the world
_ + _ = _ _ - _ = _
以x24-y212=-1的焦点为顶点,顶点为焦点的椭圆方程为( )
二元一次方程x+2y=7的正整数解有( )