题干
—Do you think our teacher is ？
—Yes， he always corrects our homework and prepares his lessons .
—Yes， he always corrects our homework and prepares his lessons .
A：careful； careful
B：careful； carefully
C：carefully； carefully
D：carefully； careful
答案(点此获取答案解析）
B
，过其右焦点且垂直于实轴的直线与双曲线交于M、N两点，O是坐标原点.若
，则双曲线的离心率为 （ ）.