Abrade the sensor surface with 300-400 grade wet-and-dry paper until the surface is clean, the two carbon electrode surfaces are clearly visible, and the surface wets out freely.

• 用300-400号（或：300-400%23）耐水砂纸擦拭传感器表面，直至将其表面清理干净，两个碳电极表面清晰可见，该表面可以自由湿润为止。”