If circumstances permit , use of layered multi - sand filter comprising both coarse sand and fine sand as filter materials fitted with automatic backwash self - cleansing device is desirable 如情况许可，宜使用包括粗沙和幼沙作为过滤物料的层沙过滤器，而过滤器应设有自动反冲的洁净装置。
23 if circumstances permit , use of layered multi - sand filter comprising both coarse sand and fine sand as filter materials fitted with automatic backwash self - cleansing device is desirable 23如情况许可，宜使用包括粗沙和幼沙作为过滤物料的层沙过滤器，而过滤器应设有自动反冲的洁净装置。
This experiment has proved that the incorporation of formative assessment with summative assessment is a solution to the negative backwash caused by the current assessing system 改革实验证明：实行形成性评价无疑是改进现存评价体系，克服以终结性评价为主的考试制度的负面效应的一个重要措施。
The last backwash of the westward movement followsthe backwash which was to solve the seemingly inextricable diplomatic difficulties , and to put an end to the military unrest of the period 来自西方的行动遇到了最后一次逆流。这股逆流必须解决外交上似乎无法解决的难题，结束这一时期的军事行动。
The implement being performed in primary and secondary schools highly promoted the quality education which emphasizes the cultivation of the students " creative spirit and practicing competence , thus aroused the strong backwash not only in the field of education but in the whole society 在中小学实施研究性学习有力地推动了以培养创新精神和实践能力为重点的素质教育，在教育界以及全社会引起了强烈的反响。
Further , full - scale experiments were carried out and the results demonstrated that the up - flow filtration with coarse media was efficient in removal of suspended solid , backwash of cleaning , and long action cycle . an effluent turbidity of 1 ntu was always achieved with an average filtration rate of 20 m / h 生产规模的运行实验显示粗石英砂滤料上向流过滤对悬浮颗粒的去除是有效的，反冲洗干净彻底，过滤周期长，当平均滤速为20m h时，出水浊度为1ntu 。
The results showed : fiber ball has the highest efficiency among the three , its water - consumption is small in backwash and it is more wear - resisting ; the comprehensive property of quartz grain filter material is poorer ; manganese grain has an effective removal of fe ( superscript 2 + ) and mn ( superscript 2 + ) but water - consnmption is big 结果表明纤维球滤料除铁滤速高，反冲洗耗水量小且耐磨损；石英砂滤料综合性能次之；锰砂虽然除铁效果较好，但反冲洗耗水量大。
As backwash is the key of renewing and keeping up the function of filter , so some factor optimization experiments of backwash have been done . the optimum operating parameters of air scour and water backwash of ceramics media are chosen by multiple factors experiments : qa = 15 l / s ? m2 , qw = 5 l / s ? m2 , t1 = 1min , t2 = 5min , t3 = 5min 经多组实验正交分析结果后得出了涂铁陶粒滤池反冲洗实验的最佳参数组合：气冲强度15l / s ? m2 ，水洗强度5l / s ? m2 ，单气预冲1min ，气水同时反冲洗5min ，单水漂洗5min 。
Education should know and utilize educational criticism resource , respond to its comment , and create good conditions for the development of educational criticism . education should put up a flat roof of elevating the making of educational criticizer , promote the development of higher education and construct the system of lifelong education and learning society . in conclusion , through scanning educational criticism , which is a social and educational phenomenon with great backwash , the paper bends itself to explore good ways for educational criticism and educational development of the 21st century 要正确认识和积极面对教育批评，教育必须正确认识教育批评的来由和价值，敢于承担责任，保持理性;要合理开发和利用教育批评资源，对民众批评强烈的话题进行甄别和研究，和批评界交往与对话，并正视问题、积极改进;还要努力搭建提升教育批评者素质的平台，加快高等教育的发展，并构建终身教育体系和学习型社会，以此为教育批评的发展与提升创造良好的生态环境和条件。
Regional theory directs space locating of daily urban system periphery in daily urban system or broader region range . centre - periphery theory require the development of daily urban system periphery think over radiant function of daily urban system center , and try to make trickling - down effect have more power than backwash effect . competitive edge theory and innovation theory explain that daily urban system periphery plays an important role in daily urban system in chongqing municipality and supports a selected measure of accelerating development in beibei district 区位理论指导着都市圈外围区在都市圈及更大区域范围中的空间定位；核心一边缘理论则要求，都市圈外围区的发展应充分考虑都市圈核心区的辐射作用，并积极实现“涓滴效应”强于“回波效应” ；竞争优势理论和创新理论则认为，都市圈外围区在重庆都市圈中将会扮演重要角色，也支撑着北暗区实现加速发展的途径选择。
