A:Thank
B:Good , thank you
C:Quite well, thank you
D:Very good
椭圆x2m+y26=1的焦距为2,则m的取值是 ( )
如图,四边形ABCD内接于圆O,AB为圆O的直径,CM切圆O于点C,∠BCM=60º,则∠B的正切值是( )