题目

After graduation she reached a point in her career ___ ___ she had to decide what to do. A. that    B. what C. which D. where 答案：D。 解析: where在此引导定语从句，修饰先行词point（不是career），又如：We have reached a point where a change is needed. 我们到了必须改一改的地步。某化学实验探究小组对一暗紫色固体化合物A进行实验，实验过程如下图．请回答下列问题：（1）写出下列物质的化学式：A______；B______；E______；F______；G______（2）写出A受热分解的化学方程式：______ K2MnO4+MnO2+O2↑