grid positive-driven condition

例句：

1. 1.The grid of the city is designed toprevent flooding during heavy rains.
   城市的网格设计是为了在大雨时防止洪水。
2. 2. Theengineer used a grid to support the roof.
   工程师用一个网格来支撑屋顶。
3. 3. Thescientist discovered a new pattern in the gridof the stars.
   科学家在星星的网格中发现了一种新的模式。