middle surface

例句：

1. 1. The car's middle surface is smooth and shiny.
   这辆车的中间表面光滑且有光泽。
2. 2. The scientist used a microscope to examine the middle surface of the sample.
   科学家使用显微镜检查样本的中间表面。
3. 3. The engineer designed the middle surface of the bridge to be smooth and safe for pedestrians.
   工程师设计了桥梁的中间表面，使其对行人来说既平滑又安全。