1. A pilot noticed a balloon which seemed to be making for a Royal Air Force Station nearby.
    一位飞行员注意到有一个气球似乎朝着附近的皇家空军基地飞去。

2. An electric fan keeps the air in circulation.
    电扇使空气流通。

3. Air is a fluid but not a liquid, while water is both a fluid and a liquid.
    空气是流体不是液体, 水是流体也是液体.

4. Air is a mixture of gases.
    空气是各种气体的混合物。

5. An air-hostess told us to keep calm and to get off the plane quietly as soon as it had touched down.
    一位女乘务员叫我们保持镇静，等飞机一着陆，就立刻平静地离开飞机。

6. Assuming that his family had been killed during an air raid, Hans settled down in a village fifty miles away where he had remained ever since.
    汉斯以为全家人都在空袭中遇难，于是便在距此50英里外的一座村子里定居下来，直至当日。

7. A pilot noticed a balloon which seemed to be making for a Royal Air Force Station nearby.
    一个飞行员发现了一只气球，它像是正飞往附近的一个皇家空军基地。

8. At this altitude, the air is very thin and the weather is uncertain.
    在这样高度上，空气十分稀薄，气候变幻无常，

9. Air and water would be constantly recycled.
    空气和水不断地再循环。

10. All air in Billion City would be passed through a cleaning system to remove dust particles, pollen, noxious gases and other pollutants.
    十亿人口城市中所有的空气都通过净化系统来消除灰尘、花粉、有害气体及其它污染物。