flat section

例句：

1. 1. The engineer used aflat section to make the machine more efficient.
   工程师使用一个平面部分使机器更加高效。
2. 2. The car's flat section isdesigned to reduce wind resistance.
   汽车的平面部分设计来减少风阻。
3. 3. The flatsection of the bridge was damaged during thestorm.
   桥梁的平面部分在风暴中受损。