能见度为零的

例句：

1. 1.The sky was overcast with low visibility due to the heavy fog.
   由于浓雾，天空的能见度很低。
2. 2.The pilot reduced the altitude to increase visibility for the passengers.
   飞行员降低了高度，以增加乘客的能见度。
3. 3.The city's air quality has significantly improved since implementing stricter environmental regulations.
   自从实施更严格的环境法规以来，该城市的空气质量已经显著改善。