available length

The research focuses on the nature, function and features of senior school elective Chinese courses, in the hope of accumulating practical experience for the design and application of senior school elective Chinese courses, discovering general, regulatory methods and processes directing the elective Chinese courses design and practice within the operational.

本文首先叙述了1997年“唐诗欣赏”选修课和2001年“外国文学导读”选修课的开设过程，呈现了这几个选题未能获得成功的原因，认识到：(1)试图用选修课的手段达到为必修课“补课”的目的，不考虑学生的个性需求，教学缺乏趣味性，是行不通的；(2)与学生的学习现状缺乏必要的联系，对学生的实际需要毫无帮助或者帮助甚少，试图建立“世外桃源”式的选修课，“有趣”有余而“有用”不足，也是不行的。

It is discussed preliminary that recovering valuable minerals from the precipitate of smelter wastewater to develop and utilize the discard and save resource.

为了节约资源,开发利用废渣,对从冶炼废水沉淀物中回收有用矿物进行了初步探讨。

The experimental research of the useful power of centrifugal mill;

离心磨矿机有用功率的试验研究

The driving and useful power of the mills are analyzed.

分析了球磨机的驱动功率、有用功率，建立了数学模型和计算方法。

Review of the practice on recycling useful ingredients from ore tailing;

回收尾矿中有用成分的实践探讨