科学探究是同学们进行化学学习的一种重要方式．它主要包含下面这几个要素：提出问题、猜想与假设、制定计划、进行实验、收集证据、得出结论等．请阅读下面内容，针对金属镁进行有关探究．

镁和铁、铜、铝一样，是一种用途广泛的金属，金属镁可用于制造航天材料、各式各样的合金等，一些烟花和照明弹里也含有镁粉．

下列各项中，不含同源染色体的是（   ）

阅读下面短文, 从短文后各题所给的四个选项(A、B、C、D)中, 选出可以填入空白处的最佳选项。
    In the 4th century, there was a man called Saint Nicholas in Myra. He was very rich and 1 to help others. He also cared for the 2 very much. He often 3 many kinds of gifts, money and other 4 things to the houses of the poor. He did this at night 5so that no one knew, because he wanted no 6 . He just wanted to help others. At that time, there were three poor 7 in his town. Both of their parents died. They could hardly 8 enough money to make a living. Nicholas felt sorry for them and 9 to do something to 10 them. On Christmas Eve, when everyone was11 , Nicholas walked through the streets to the house where the three sisters lived. Quietly, he 12 onto the roof and dropped three bags of 13 into the chimney. It so happened that the three sisters had 14 their stockings before they went to bed. The stockings had been 15 by the fire to dry. When Nicholas dropped the gold, each bag fell into a stocking. The three sisters were surprised and 16 to find the three bags of gold in their stockings the next morning. Now they didn't have to worry about their 17 as they could use the gold to get food. Soon, the story began to get around. Other 18 began to hang up stockings on Christmas Eve 19 finding bags of gold when they woke up the next morning.
    Over the years, Saint Nicholas became associated (有联系的)with Christmas. The 20 of hanging stockings up by the chimney on Christmas Eve is known all over the world. And Santa Claus, famous for the red cape (斗篷)and the white beard, became the most popular guest to children on Christmas.

阅读材料，完成下列要求。

材料一  中国古代监察官员，在行使监察权力之时，监察机关与监察官员以法律为准绳依法监察。历朝对于严格监察官员的选任主要奉行三条原则：其一，注重监察官员的基本素质。其二，注重在具有实际政治经验和有良好治绩的各级官吏中选拔监察官。其三，晋升从优，出将入相。御史台至东汉时已开始独立行使职权，魏晋以后成为皇帝亲自掌握的机构，台官的地位也相对独立，往往不受台主牵制，而直接向皇帝上章弹奏。......宋朝时加大对失职者责任的追究，监察官员倘有滥用权力,如有案件长期积压、定罪量刑错误、钱粮埋没等项依律处理。

——摘自杨丛樱《中国监察制度的演进》

材料二  中国古时举行考试和监察制度，也有很好的成绩，像满清的御史，唐朝的谏议大夫，都是很好的监察制度......。有一切的灾难只有一个原因，那就是普遍的又是有系统的贪污。只有用根绝官吏贪污的办法才行。因此，中国的前途“只有革命”。

政权就可以说是民权。民权是新力量，政府是旧机器，我们现在要解决民权问题，便要另造一架新机器，是要分开权和能。人民是要有权的，机器是要有能的。我们防止一切的流弊，便要采用外国的行政权、立法权、司法权，加入中国的考试权和监察权，建成一个很好的完璧，造成一个五权分立的政府。

——摘编孙中山的一次演讲

韩非子在描述远古社会自然环境时，写道：“上古之世，人民少而禽兽众，人民不胜禽兽虫蛇。”因此，古人最需要的是（  ）