农村寄宿制学校的公共区域应设置方便学生洗手的水龙头,原则上每个水龙头服务学生人数不超过()人。
参考答案:50
____________professional violinist practices for several hours a day, but____________ violinist has his own way of playing the Beethoven concert.
A.Each, every
B.Every, each
C.One, a
D.All, each
浸出制剂