Wipe these surfaces with a damp cloth to ensure they are clean and free from any debris.
用湿布擦拭这些桌面，确保桌面干净没有任何碎屑。
The surfaces to be joined must be clean and free from oil, grease and heavy oxides.
连接部位表面必须清洁，没有油污、油脂和氧化物。
Surfaces in contact with the fluid shall be free from scale and annealing colours.
与流体接触的材料表面不得有刻痕和退火变色。
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