A:若ma=mb,则ca>cb
B:若ma=mb,则ca<cb
C:若ca=cb,则ma=mb
D:若ca=cb,则ma>mb
已知点A(1,1)是椭圆 x2a2+y2b2=1 (a>b>0)上一点,F1,F2是椭圆的两焦点,且满足|AF1|+|AF2|=4.
(I)求椭圆的标准方程;
(II)求过A(1,1)与椭圆相切的直线方程;
(III)设点C、D是椭圆上两点,直线AC、AD的倾斜角互补,试判断直线CD的斜率是否为定值?若是定值,求出定值;若不是定值,说明理由.
补全对话,每空一词。
A: ____ time do you usually get up, Bob?
B. I usually get up ____ 6 o'clock.
A. So early? What do you do then?
B: I ____ my teeth and ____ a shower. Then I eat my breakfast.
A: ____ do you go to school?
B: At 8 o'clock.