air clearance

• 空隙

air clearance的用法和样例：

例句

1. There was a clearance of only ten centimetres between the two walls.
   两堵墙之间只有十厘米的空隙。
2. When fibers swell, they fill the air spaces and thus reduce ventilation.
   一般纤维膨胀后，占据了空隙，因而减少了通气能力。