芦苇状的

First, select four kinds of main risks source from bigly celebrate the main risk in region source, namely the flood, drought, sand-dust weather and petroleum pollution accident, etc. According to the different a request for to habitat, study this 19 kinds of landscapes ecosystem type of the Regional induce for 7 kinds of ecosystems system: Then the marsh of bulrush, lakes and reservoirs , salt alkali wasteland, prairie, island form wood, farmland, town. The difference is proceeded by characteristic according to each type ecosystem to the analysis of four kinds of main risks source, including the certain risk all rate, delimiting the space distribute, analyzing the risk strength to the receptor etc. At proceed the revelation the different from endanger to analyze the inside, this text borrows ecosystem index number that this index sign to reflect primarily habitat the ecosystem meaning of the type of habitat the different from position, with weak an index number to show the destructibility of the habitat, from but compute each ecosystem that is lost by ecosystem system an index number.

首先，从大庆地区主要的风险源中遴选出四种主要的风险源，即洪涝、干旱、沙尘天气和石油污染等；依据不同生物类群对生境的要求，将本研究区域的19种景观生态类型归纳为7种生态系统：即芦苇沼泽、湖泡库渠、盐碱荒地、草甸草原、岛状林、农田、城镇；对四种主要风险源的进行分析，包括确定风险概率，划定空间分布，对风险受体的作用强度分析等；在进行暴露和危害分析中，本文主要借生态指数这一指标来反映不同生境类型的生态意义和地位，以脆弱度指数来体现不同生境的易损性，从而计算出各受体生态系统的生态损失度指数；由于各主要风险物质对风险受体的作用强度是不同的，对形成区域性生态风险的作用大小也有差异，因此本文采用层次分析法对主要生态风险物质进行综合评价，并把判断矩阵排序权值的合理计算问题归为—非线性化问题，并提出用基于遗传算法(GA[5])的层次分析模型进行权重分析；进行风险表征，即综合前面两个阶段的信息，对环境中风险的性质和强度以及风险评价过程中不确定性问题进行分析与描述，并划分出五级生态风险区；最后，根据划分的五级生态风险区的特征，分别提出针对各生态风险区的生态风险管理对策。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。