下列有关化合价的说法中，正确的是（　　）

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                                                                                                                        清平乐 · 独宿博山王氏庵     辛弃疾
                                                                                                       绕床饥鼠，蝙蝠翻灯舞。屋上松风吹急雨，破纸窗间自语。
                                                                                                       平生塞北江南，归来华发苍颜。布被秋宵梦觉，眼前万里江山。