A：生产关系应适应生产力的要求
B：政治制度决定制定法规实践的变化
C：上层建筑应适应经济基础的要求
D：社会意识能脱离社会存在而发展
Many students take the school bus to school every day. Parents think taking the school bus is usually safe (安全的), but sometimes it is dangerous. Some students don't keep the school bus rules. What are the school bus rules?
Arrive at the bus station early.
Wait for (等候) the school bus at the bus station.
Don't run at the bus station.
Don't walk or fight on the bus.
Don't get off (下车) the bus when it goes.
植树时，先确定出两个树坑的位置，从而确定一行树坑的位置，这是因为____
由幂函数y=x12和幂函数y=x3图象围成的封闭图形面积为（ ）
