近几年的竞赛及中考中经常出现一些题干内容看似简单,却不容易得分的试题。题干中的某些描述(或装置)常常隐含着解题所必需的知识内容,而这些知识内容往往成为解题的瓶颈。只有充分挖掘隐含知识,才能突破瓶颈并顺利解决问题。现举例分析: 例1 为验证人体呼出气体中含有的CO_2不 In recent years, competitions and senior high school entrance examination often appear some of the title content seems simple, but not easy to score the questions. Some descriptions (or devices) in the title often implicate the content of the knowledge necessary for problem solving, and these knowledge contents often become the bottleneck of problem solving. Only by fully excavating hidden knowledge can we break through the bottleneck and successfully solve the problem. Now an example analysis: Example 1 to verify the human body exhaled gas contained in CO2 does not