subsonic flow

例句：

1. 1. The subsonic flow of the river is calm and peaceful.
   河流的亚音速流动是平静和宁静的。
2. 2.The subsonic flow of the air is so quiet that you can hear a pin drop.
   空气的亚音速流动是如此安静，以至于你能听到一根针掉落的声音。
3. 3. The subsonic flow of the water is so gentle that it feels like a warm embrace.
   水的亚音速流动是如此温柔，它感觉像是温暖的拥抱。