we deeply discuss the importance of choosing sample sapce in two sides : one is the calculation of classical model of probability, the other is the independency of events, and the concept of probability should be fully used in the calculation of probability 摘要從古典概型中事件概率的計算和事件的相互獨立性兩個方面,通過舉例較深入地分析了樣本空間選取的重要性,并指出在概率計算中要充分利用概率概念。