决定人的性别的时期是（ ）

                                                                                                           渡湘江
                                                                                                       ［唐］杜审言
                                                                                         迟日园林悲昔游，今春花鸟作边愁。
                                                                                         独怜京国人南窜，不似湘江水北流。
     ［注］杜审言：杜甫的祖父，仕途失意，当时被贬去僻远的峰州，《渡湘江》写于此时。