---        they are talking to each other!

---Yes. They are really happy to see each other.

A．What excited

B．How excited

C．What excitedly

D．How excitedly

阿旺同学想自制牙膏，他在网上查阅资料得知牙膏配料中加入纯度高的轻质碳酸钙粉末，它是用石灰石的原料经分解．化合等反应精制而成（氧化钙溶于水生成氢氧化钙）．其原理有关变化的化学方程式为：

（1）______；（2）______；（3）______．