It was Sunday yesterday. The weather was fine. It was sunny and there were no clouds in the sky. Sandy and Sue got up early in the morning. Now they were in the park. It is a big park and it's so beautiful. They saw many people there. Some boys played football on the grass. Some girls danced under the tree. An old man walked beside the lake. A young woman and her little son looked at the fish in the lake. How happy they are!

黄土高原和云贵高原分别为中国28个土壤保持生态功能区之一．读图回答问题．

麦考莱在《英国史》中说，“对1688年革命所能作的最高赞颂乃是：它是我们的最后一次革命”，此后人们相信“影响宪政所需的每种改进都可在宪政本身内部找到”。符合麦考莱观点的是（    ）

下图是某个农业生态系统的结构模式图，该图中表示生态系统能量流动的箭头是（   ）

①3个铁原子____②镁元素____ ③氢氧根离子____

④2个硝酸根离子____ ⑤5个铵根离子____．