calibration mark

例句：

1. 1. The engineer used acalibration mark to ensure the accuracy ofthe measurements.
   工程师使用一个校准标记来确保测量的准确性。
2. 2. The machine'scalibration mark was removed before we coulduse it.
   在我们可以使用时，机器的校准标记被移除了。
3. 3. The calibrationmark on the scale is essential foraccurate weight measurement.
   秤上的校准标记对于准确的重量测量至关重要。