The teacher tells us that ______ careful we are, ______ mistakes we will make.
____ ____sad.
过椭圆C:x2a2+y2b2=1a>b>0的左顶点A的斜率为k的直线交椭圆C于另一个点B,且点B在x轴上的射影恰好为右焦点F,若13<k<12则椭圆离心率的取值范围是( )