A:(x+3)2+y2=4
B:(x-3)2+y2=1
C:(2x-3)2+4y2=1
D:(x+)2+y2=
已知方程x22-k+y2k-1=1的图象是双曲线,那么k的取值范围是( )
The public bikes are r____ by many tourists along the West Lake.
如果a>0,a一定大于 1a 。