<Abstrcat>Durations of early developmental stages, including embryonic development (De) and pre-reproductive period (Dp) of three strains of Brachionus angularis collected from Qingdao (QD strain), Guangzhou (GZ strain) and Wuhu (WH strain) cities respectively, were studied at 25℃, and with five concentrations (0.

Taking the urban wastewater as investigation objective,the influence of stepped operation time,hydraulic retention time (HRT),density of dissolved oxygen(DO),and sludge retention time (SRT) on the efficiency of biological nitrogen removal with integrated activated sludge processing was investigated and,then,several improving measures of the design and operation with this technique were discussed.

It takes two hundred years from the mid -19~(th) century to the mid -21~(st) century for the Chinese nation to rise from degradation to rejuvenation and this period may be divided into six historical stages.

It is pointed out in this paper that the ethnic group transference in this region can be divided into six historical phases and each phase presents different characteristics.

Based on the analysis of the historical development of Chinese modernization,the paper divides the historical stages,reveals the tasks and characteristics of political development in different stages,and discusses the necessity of the choise of the political development of socialism with Chinese characteristics.