In the experiments of potted plant and middle-system, we researched dephosphorization efficiency of different plants in underground-ditch-pattern soil treatment and artificial wetland.

采用盆栽实验和中试实验系统，研究了地沟式土地处理系统和人工湿地中不同植物对磷的去除效率。

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President Obama said the current system has led the country to a breaking point, imposing hardships on middle-class Americans who struggle to pay for health care, who are unable to obtain it.

VOA: standard.2009.09.10

And, Aristotle gave us this system, which persisted almost through the Middle Ages. And, Aristotle gave us this, and I'll leave you with this.

他带给我们这个系统，一直统领着我们,直到中世纪，亚里士多德给了我们这个，你们自己看吧。

麻省理工公开课 - 固态化学导论课程节选

In its School Organisation Review, Suffolk County Council is replacing the three-tier system of primary, middle and secondary schools with the two-tier system which cuts out the 40 middle schools.

BBC: Suffolk's middle schools closure programme starts

In April 2005, the council agreed in principle to change from the current system of first, middle and high schools to a system of primary and secondary schools.

BBC: NEWS | UK | England | Tyne | School shake-up talks to continue

Frustration in the universities is matched by outrage among Tories, who are afraid of damaging standards and biasing the system against middle-class applicants.

ECONOMIST: Public-service reform