下列物质中是晶体的一组是（　　）

阅读下面两首诗。
                                                                                【甲】早春呈水部张十八员外·韩愈
                                                                                 天街小雨润如酥，草色遥看近却无。
                                                                                 最是一年春好处，绝胜烟柳满皇都。
                                                                                           【乙】赠刘景文·苏轼
                                                                                  荷尽已无擎雨盖, 菊残犹有傲霜枝。
                                                                                  一年好景君须记, 正是橙黄橘绿时。