A:必在圆x2+y2=2内
B:必在圆x2+y2=2外
C:必在圆x2+y2=2上
D:必在圆x2+y2=1与圆x2+y2=2形成的圆环之间
你是否种过植物?说说怎么样种植?
- Who is your best friend? ( )
- __________