angle of friction

例句：

1. 1.The car's engine needs to be tuned for optimal performance.
   汽车的引擎需要调校以获得最佳性能。
2. 2. The angle of the roof is important for ventilation.
   屋顶的角度对于通风很重要。
3. 3. The angle of the blades affects the efficiency of the machine.
   叶片的角度影响机器的效率。