1　我在演示浇冷水使刚刚止沸的开水重新沸腾时并没采取教材中浇淋的方式 ,而是拿一个常用的薄塑料方便袋装上适量冷水或冰水冷敷烧瓶底部 ,如图 1所示。这样既可以避免浇淋时流水四溅 ,又可以避免流水对瓶内开水冷却降温所带来的不利影响 ,从而延长了二次沸腾的持续时间。而且 1 In the demonstration of pouring cold water to boil the boiled boiling water, I did not use the method of pouring water in the textbooks. Instead, I used a commonly used thin plastic convenience bag to put the appropriate amount of cold water or ice water on the bottom of the cold flask, as shown in Figure 1. . This will not only avoid the splashing of water when pouring, but also avoid the adverse effect of running water on the cooling and cooling of the boiling water in the bottle, thereby prolonging the duration of the secondary boiling. and