甲、乙为短周期同一主族元素组成的单质，丙、丁为氧化物，它们存在如下转化关系，则满足条件的甲和乙分别为（   ）
  

增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。

删除：把多余的词用斜线(＼)划掉。

修改：在错的词下画一横线，并在该词下面写出修改后的词。

注意：

1）每处错误及其修改均仅限一词；

2）只允许修改10处，多者(从第11处起)不计分。

    In the summer holiday following my eighteen birthday, I took driving lessons. I still remember how hard first day was. Before getting into the car, I thought I had learned the instructor's orders, so once I started the car, my mind goes blank. I forgot what he had said to me altogether. The instructor kept repeating the word, “Speed up!” “Slow down!” “Turning left!” I was so much nervous that I could hardly tell which direction was left. A few minutes late, the instructor asked me to stop the car. It was a relief and I came to a suddenly stop just in the middle on the road.

下列式子成立的是（    ）