A:How come
B:What do you recko
C:What for
D:So what
已知a,b 满足a+2b=1,则直线ax+3y+b=0必过定点 ( )
已知椭圆C: x2a2+y2b2=1 (a>b>0)的离心率为 33 ,直线l:y=x+2与以原点为圆心、椭圆C的短半轴为半径的圆O相切.