复沟型水沟系的水流途径是：入水小孔---流入管---前幽门孔---辐射管----后幽门孔-----流出管----中央腔---出水孔。（）
参考答案：错
The Education Department says that school safety has set off alarm bells with frequent reports of serious
accidents______ students got injured or killed. [ ]
A. after which
B. in which
C. by which
D. for which
被称为继北魏贾思勰《齐民要术》之后又一部古代农业科技的重要文献的是泰和曾安止的（）
A.《农器谱》
B.《农书》
C.《禾谱》
D.《齐民要术》
