Considering the subnormal subgroups,some equivalent conditions for nilpotency of finite groups are given and a sufficient condition for nilpotency of finite groups is obtained.
Peter also said he had a crush on the eldest hasty sister and had been rejected, while all the hasty children had mocked Peter for being educationally subnormal, as the British put it.
Indeed it seems capable of remaining in a chronic condition of subnormal activity for a considerable period without any marked tendency either towards recovery or towards complete collapse.