阅读《夜雪》，答题。
                                                                                                   夜雪
                                                                                                  白居易
                                                                                      巴讶衾枕冷，复见窗户明。
                                                                                      夜深知雪重，时闻折竹声。
     【注】这首五绝作于公元816年(元和十一年)。白居易时年四十五，贬任江州司马。