如图，为生态系统中部分组成成分示意图、请回答．

（1）除鹭鹚外，还有哪一种生物对鱼鹰的生存最为不利？______．

（2）______的生长状况对于生态系统内生态平衡的维持起着最为重要的作用．

（3）鱼鹰和鹭鹚被大量捕杀后，短期内河豚、鳗鲡的数量变化情况是______．

（4）蜗牛、河豚之间的关系，既是______关系，又是______关系．

（5）单从组成生物体的细胞结构来看，高等的水生植物与鱼鹰相比所具有的细胞结构有______．

（6）假设此生态系统中的水被有机汞污染了，水中有机汞的浓度为0.05ppM，生物A，B，C体内残留有机汞的浓度分别是7，0.51，68（单位是ppm），那么C所代表的生物可能是图中的______．

（7）在生态系统的物质循环过程中，生物体内的______生理过程与二氧化碳在生物圈中转化有关．

The purpose of the requirements definition phase is to produce a clear, complete, consistent, and testable (16) of the technical requirements for the software product.

During the requirements definition phase, the requirements definition team uses an iterative process to expand a broad statement of the system requirements into a complete and detailed specification of each function that the software must perform and each _( 17) that it must meet. The starting point is usually a set of high level requirements from the (18) that describe the project or problem.

In either case, the requirements definition team formulates an overall concept for the system and then defines (19) showing how the system will be operated publishes the system and operations concept document and conducts a system concept review (SCR).

Following the SCR, the team derives (20) requirements for the system from the high level requirements and the system and operations concept. Using structured or object-oriented analysis, the team specifies the software functions and algorithms needed to satisfy each detailed requirement.

18（）

A.producer

B.customer

C.programmer

D.analyser