用所学知识回答下列问题．

（1）氟化钠是某些牙膏的添加剂，能有效预防龋齿．如图是氟元素在周期表中的相关信息及钠原子结构示意图，则氟元素的原子核外电子数是 ____，钠原子在化学反应中易 ____（填“失”或“得”）电子．氟化钠可以用钠与氟气（F₂）反应制得．反应的化学方程式是 ____．

（2）氢、碳、氧、钙等元素能组成多种物质．A的化学式是CaO，俗称 ____，A与B（胃液中含有的酸）反应放出大量的热，该反应的化学方程式是 ____．用化学式表示3个碳酸根离子 ____．

国运兴衰，系于教育

根据短文内容，选择正确答案。
   It’s Sunday morning．There are many people in the park，some boys  are playing basketball．There are some girls under a big tree．They’re singing and dancing．What are those women doing? They are drinking tea．Look at the woman in a blue coat．Who's she? She’s my mother．She is talking to Lin Feng．Lin Feng is her student．He is a good student．He studies hard．He’s good at all the subjects． And he's friendly to all his teachers and his friends．