The error can be avoided by increasing the gear grinding allowance in length of common normal line to grind gear.

此误差可通过在公法线长度方向上加大留磨量，进行磨齿予以消除。

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Here are some of the common methods for calculating an allowance.

FORBES: How Much You Should Pay Your Kids For Allowance

While the number of young people claiming Jobseeker's Allowance in Ludlow remains well below the national average, the group said low incomes common in rural areas disguised the full picture.

BBC: South Shropshire poverty 'on the rise'