2005年高考(江苏卷)的第18题是全卷最有分量的一道压轴题.此题取材于中学物理中典型的碰撞模型,物理情景新、能力立意高,有很好的区分度.不过,笔者觉得参考解答中对第(4)小题的解答似乎不够完整,还有一种情形需要补充.图1考题:如图1所示,三个质量均为m的弹性小球用两根长均为L? The 18th issue of the 2005 college entrance examination (Jiangsu reel) is the most influential title question for the whole volume. This question is based on the typical collision model in middle school physics. It has a new physical situation, high competency, and a good differentiation. The author finds that the answers to the (4)th question in the reference answer seem to be incomplete, and there is a case that needs to be supplemented. Figure 1 Exam questions: As shown in Figure 1, three elastic balls with mass m are two long Are all L?