下图是两个生态系统中腐殖质总量随时间而发生变化的情况，甲、乙曲线分别代表哪两个生态系统（ ）
江南水乡以河成街，街桥相连。读江南水乡景观图，回答问题。
请运用所学地理知识分析上述景观的形成原因。
— _____ will your father return home? It's a long time since I saw him last time.
— Just in two days.
