题目

某元素的原子结构示意图，利用该元素组成的单质可测定空气中氧气的含量，实验装置如图2所示。                    （1）该元素原子的核电荷数为       ，在化学反应中该原子易        电子； （2）图2所示装置中发生反应的化学方程式为                                            。At 9 yesterday morning, I _________an English class while they ___________P.E.A. was having, were havingB. had, hadC. was having, had