题目

 —Look，the light in Jim’s room is still on. Do you know­­______?  —To study for the coming exam, maybe. A. if he works hard                                     B. why is he so busy         C. why he stays up so late                           D. when he will stop working 答案：C 已知点M(，0)，椭圆＋y2＝1与直线y＝k(x＋)交于点A、B，则△ABM的周长为 [　　] A． 4 B． 8 C． 12 D． 16