It is the root circle of the external spline or the inside circle (tooth tip circle) of the internal spline.

它是外花键的齿根圆，和内花键的内圆(齿顶圆)。

youdao

Long distance voice saws Zhizuan ears, it is the voice of restless disturbed my thoughts, and forced out the door too, in the promise a large pocket on the inside circle of the courtyard.

远处长长的电锯声直钻耳孔，令人焦躁不安的声音搅乱了我的思绪，不得已，出得门来，在诺大的院落里兜上一圈。

youdao

Two hundred deer and more came running inside the circle at once, and the huntsmen shot them.

二百多只鹿立刻跑进了圈子，猎人们把它们射杀了。

youdao

Inside the circle, given away by its small helical pattern, is a smear of dna dried onto its surface.

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But the size of the zone would grow dramatically if the government eventually includes all land inside a circle encompassing the newly listed cities.

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In the dirt along a levee, about 10 miles deep into the wetlands, Rubinstein found a gold pendant, with sapphires forming a cross inside a circle of diamonds.

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