题目

阅读理解 阅读下面短文，然后根据短文内容，在每小题所给的四个选项中选出最佳选项。When we talked about intelligence(智力), we d o not mean the ability to get good scores on certain kind of tests or even the ability to do well in school. By intelligence we mean a way of living and behaving, especially in a new situation. If we want to test intelligence, we need to find out how a person acts instead of how much he knows what to do.For example, when in a new situation, an intelligent person thinks about the situation, not about himself or what might ha某同学为测定空气里氧气的含量，设计了下图所示的实验装置．该同学在“化学性质稳定的金属梯”的每一步的凹处放置一颗用滤纸吸干水后的白磷，用放大镜会聚6V手电筒光于靠近水面的一步“金属梯”处的白磷上．(白磷极易燃烧，燃烧现象、反应和红磷一样）请回答下列问题：（1）整个实验过程中，可观察到的现象是_______________________；该反应的符号表达式为：_________________________。（2）“金属梯”的每一步上都放置一小颗白磷与只靠近水面的一步“金属梯”处放一大颗白磷相比，优点是 __________________ ；（3）解释冷却到室温后所产生现象的原因______________ ．