题干
The operation was successful, but I still felt _____.
A：very painful
B：much painful
C：a lot of pai
D：very paining
答案(点此获取答案解析）
C
A：very painful
B：much painful
C：a lot of pai
D：very paining
，离心率
的椭圆两焦点为
，过
作直线交椭圆于
两点，则
的周长为（ ）
