题目

有A、B、C、D四种短周期元素, 它们的原子序数由A到D依次增大, 已知A和B原子有相同的电子层数, 且A的L层电子数是K层电子数的两倍, C燃烧时呈现黄色火焰, C的单质在点燃条件下与B的单质充分反应, 可以得到与D单质颜色相同的淡黄色固态化合物, 试根据以上叙述回答: 1.元素名称: A ________ B __________ C __________ D ___________ 2.写出AB2 的电子式为 ________________________； 3.用电子式表示化合物 C2D 的形成过程 _________________________________。  What’s your favorite subject? English．P．E．or science? Perhaps different students will give different answers．Now，more and more schools have started to add（增加）survival education（生存教育）to their everyday lessons．Do you like this subject? I'm sure you will give a “yes” answer．The Sichuan earthquake made people realize the importance of survival education． At the beginning of the fall term，CCTV played a program（节目）about life education named The First Class．All the primary and middle school students in our country, watched the program at home or at school．But this special lesson for public good is certainly not enough for survival education．Students must learn it like other subjects at school． 1．What's your favorite subject? 2．Do you like survival education? 3．Is survival education important? 4．What's the name of the program of CCTV? 5．Where did the students watch the program?