课内外练习既是帮助学生理解和掌握数学基础知识，又是发展学生智力，培养学生数学能力的重要手段。同时也是教师掌握教学反馈信息、进行诊断性评价，改进教法，提高教学效率的重要一环。优化练习就是为了“在规定的时间和师生花费合理的能力下，尽可能发挥最大的效率”（... Exercises both inside and outside the class are not only helping students to understand and master the basic knowledge of mathematics, but also an important means to develop students 'intelligence and train students' mathematical abilities. It is also an important part for teachers to grasp the teaching feedback information, carry out diagnostic evaluation, improve teaching method and improve teaching efficiency. Optimize the practice is to “in the prescribed time and teachers and students to spend reasonable ability, as much as possible to maximize efficiency” (...