This thesis includes four parts, which can be classified into two pieces: theory piece and construction piece.
文章内容分为四部分，也可简单的归结为两篇：理论篇和建设篇。
2
Single row angular contact ball bearing with twopiece inner ring has complex construction, long design cycle, great difficulty in processing.
双半内圈四点接触球轴承结构复杂、设计周期长、加工难度大。
3
Explain the differences between two-dimensional (flat) shapes and three-dimensional (solid) shapes. How are the book and piece of construction paper the same?