Moreover , i will try to discuss the differences of these two editions in its basic structure , addition and erasion of the annotations , interpretations and material sources 本文讨论的重点为，为何只有第二版第二次印刷，不见第二版第一次印刷。
2.
According to its cause and characteristics of landuse , we can classify such area into two typical areas : area with soil and water erasion and area with land desert 根据其成因和西部土地资源利用特点，可将西部土地生态脆弱区划分为两种类型：水土流失严重型生态环境脆弱区和土地沙漠化型生态环境脆弱区。
3.
The control of plant ' s dynamic response and plant ' s disturbance erasion is respectively done . they do n ' t impact each other . so we can best enhance the system ' s performance and erase disturbance 自适应逆控制对对象动态响应的控制和消除扰动的控制是分别进行控制的，二者互不影响，这样就可尽量提高系统动态性能和尽可能消除干扰。
4.
As a southwesten autonomous county with national minority and typical area , the nature condition in youyang is bad and the economy falls behind and the soil erosion is serious . furthermore , the population increases quickly which results to steep slope farming and excessively opening up , so eco - environment accelerates rapidly . in the whole , youyang is an epitome of the area with soil and water erasion in western china 酉阳作为西南少数民族自治县，区内自然条件差、经济落后、水土流失严重，属典型的水土流失型生态脆弱区，加之该区生产手段落后、经济结构单一、而人口增长过快，导致人地矛盾尖锐，陡坡耕作、过度开垦，使生态环境加速恶化，因此，酉阳自治县土地资源可持续利用可以作为西部水土流失型生态脆弱区的一个缩影。
