— . Few of them would become your real friends.
A:That's for sure
B:It's not the case
C:I couldn't agree more
D:I'm pleased to know that
已知随机变量ξ服从正态分布N(0,σ2),若P(ξ>2)=0.023,则P(-2≤ξ≤2)=( )
①小孔成像; ②皮影戏;③手影; ④放电影.
关于x,y方程组x2+2y2=6mx+y=3有一组实数解,那么m的取值范围是( )