While dot punching, blue annular marks are printed at the positions of the survey dots by a coloring head under the action of a spring.

冲点的同时涂色头依靠弹簧的作用在测量点处印上蓝色圆环标记。

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While dot punching, blue annular marks are printed at the positions of the survey dots by a coloring head under the action of a spring.

冲点的同时涂色头依靠弹簧的作用在测量点处印上蓝色圆环标记。

youdao