A:
B:
C:
D:
Early this morning I was busy ____ (挖) in the garden to plant trees.
(Ⅰ)求 P 的轨迹 C 的方程.
(Ⅱ)过点 (−1,3) 的直线 l 与 C 交于 M,N 两点,且 |MN|=23 ,求直线 l 的方程.
— When did you arrive at school this morning?
—At 7:30 o' clock.