题目

Speaking of all the songs he has written, I think this is probably his _______ one. A. better-known      B. well-known         C. best-known         D. most-known 答案：C2．已知直线l：ax+by+c=0及圆P：x2+y2=1，其中a，b，c满足条件：a2+b2=k2c2，其中（c≠0，k≠0）（1）试讨论直线l与圆P的位置关系，（2）若直线l被圆P截得的弦长为1，求k的值．