题干
The boy_________ eats vegetables and _________ does sports, so he isn't healthy at all.
A：always; seldom
B：seldom; often
C：sometimes; always
D：never; seldom
答案(点此获取答案解析）
D
中，双曲线中心在原点，焦点在
轴上，一条渐近线方程为
，则它的离心率为