On my way home after school there had an accident. A heavy truck hit a bike, caused the young woman on the bike fall to the ground heavily. As a result, one of her legs broken. Blood was running down his leg. A lot of people stood by watching, but everybody gave her a hand. I hurriedly stopped a passed car, and the driver and I carried the injury woman into the car. Then we took her to the hospital of nearby. The doctors treated her in time and she is soon out of danger.

空气、水是人类赖以生存的自然资源．

（1）空气是由多种气体组成的混合物，其中二氧化碳占空气总体积的______，人类时刻都离不开空气，是因为空气中的氧气能______．

（2）天然水中含有许多杂质，将天然水变成纯水的方法是______．利用蒸发原理可以从海水中提取食盐，实验室蒸发食盐水时用到的仪器有______（填序号）．

①带铁圈的铁架台   ②酒精灯   ③漏斗   ④玻璃棒   ⑤量筒   ⑥蒸发皿．

（3）请按要求写出初中化学教材中有水生成的化学方程式：

①分解反应：______；

②化合反应：______；

③置换反应：______．