在讨论了碳纳米管的几何结构的基础上，对齿型和椅型碳纳米管的对称性进行了分析并将这些对称元进行了抽象和总结。
The geometric structure of carbon nanotubes (CNTs) is introduced, the symmetry of zigzag and armchair CNTs is analyzed and these symmetry elements are abstracted and summarized.
连贯性错误：克莱尔对双型齿翼龙开枪后，画面里太阳的位置发生了改变。
Continuity mistake: After Claire shoots the Dimorphodon the sun changes between shots.
基于有限元方法，对Y7125型磨齿机的砂轮主轴进行模态分析，得出了四阶主振动频率，并对数据进行了处理。
This paper analyzes the modal of Y7125 gear grinder spindle, gets out the main four stages of spindle vibration frequency and deals with the data.
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