题目

In many families, parents don't pay attention to teaching their children. Some parents think they only need to give their children food and clothes, and send them to schools and pay for their education. That's all. In fact, they are wrong.      We should know that parents are children's first teachers. They should also educate them. They should teach their children how to study, how to get on well with others, how to respect(尊敬)people and more. Probably the parents don't know many things, but they can give their children confidence(信心) and the good attitudes(态度) to life.    现有A、B、C、D四种短周期元素，已知A、B同主族，B、C、D同周期，A、B的原子序数之和等于C、D的原子序数之和；C为常见金属，其最高价氧化物的水化物能分别跟B和D的最高价氧化物的水化物反应。请回答：（1）B和C的元素符号分别为B_______________，C_______________。（2）上述四种元素的原子半径由大到小的顺序（用元素符号表示）为_______________。（3）D单质在A单质中燃烧的产物与二氧化碳反应的化学方程式为___________________________。（4）写出B元素在周期表中的位置_______________。（5）写出C的最高价氧化物的水化物分别跟B和D的最高价氧化物的水化物反应的离子方程式________________________；__________________________。