A:①②③
B:①②④
C:①②③④
D:①③④
已知双曲线C: x2a2−y2b2 =1(a>0,b>0)的左、右焦点分别为F1,F2,O为坐标原点,点P是双曲线在第一象限内的点,直线PO,PF2分别交双曲线C的左、右支于另一点M,N,若|PF1|=2|PF2|,且∠MF2N=120°,则双曲线的离心率为( )
People, especially teens, think it great fun to surf on Internet.
This is ______ eraser. That is ______ ruler.