摘要
选择四种具有代表性的解释加以比较，显现不同解释的共同点、差异、缺点、在不同教学阶段中的适用性，最后得出较成熟的解释。
By comparison,the author wants to shoW the common ground and difference of the different explanation.And also the application in teaching of different degrees.
出处
《青海师范大学学报（自然科学版）》
1996年第3期30-33,共4页
Journal of Qinghai Normal University(Natural Science Edition)
