A.R＞0               B.0＜R＜2

C.0＜R＜4          D.2＜R＜4

方程4x²+Ry²=1的曲线是焦点在y轴上的椭圆，则R的取值范围是

A.R>0                                                             B.0<R<2

C.0<R<4                                                         D.2<R<4

方程4x²+Ry²=1的曲线是焦点在y轴上的椭圆，则R的取值范围是

1. A.
   R>0
2. B.
   0<R<2
3. C.
   0<R<4
4. D.
   2<R<4