A:Fe:1s22s22p63s23p63d54s3
B:F ˉ:1s22s22p6
C:K:1s22s22p63s23p64s1
D:Kr:1s22s22p63s23p63d104s24p6
已知斜率为2的直线l双曲线C:x2a2-y2b2=1a>0,b>0交A,B两点,若点P2,1是AB的中点,则C的离心率等于( )
下列各项中,对《复活》故事情节的叙述有误的一项是( )