compressible cascade flow

例句：

1. 1. The air inside theballoon is compressible, so itcan be inflated or deflated.
   气球里的气体是可压缩的，所以可以充气或放气。
2. 2. Thecompressible fluids are used tomake things lighter.
   可压缩流体被用来制造轻量化物品。
3. 3. The compressiblegases are often used in refrigeration systems.
   可压缩气体常用于制冷系统。