- intermediate principal plane
- 中: hit; fit exactly
- 主: host
- 平面: plane; two dimensions; flat ...
- 主平面: baseplane; main plane; major principal plane; primary flat; primary surface; principal plane
- 第二主平面: secondary principal plane
关注微信公众号:chachacidian,回复:中主平面,即可在微信中查询翻译