一九五八年,我们在分析五年级学生算术试卷时,发现有一些四则应用问题(如“和差问题”、“差倍问题”等)学生经常解错;在学生的毕业试卷中,求未知项的问题(如已知除数和商,求被除数;巳知减数和差,求被减数),也经常出现错误。而这些问题,却都是我们在教学工作中很注意并花费精力最 In 1958, when we analyzed the fifth-grade math test papers, we found that there were some four problems (such as “Sum of Difference Problems” and “Difference Problems”), which were frequently solved by students. In students’ graduation papers, The problems of unknown items (such as the known divisors and quotient, the number of dividends; known subtractions and differences, and the number of subtractions) also often make mistakes. These problems, however, are all we pay great attention to in the teaching work and spend the most energy