第一固井界面
first cementing interface
第一类曲面积分
surface integrals of the first type
第一菱面
rhombohedron of the first order
第一菱面体
rhombohedron of the first order
第一正方底面
tetragonal base of the first order
曲面的第一基本形式
first fundamental form of surface
first fundamental form of curved surface
第一第二系弹簧挠度比
ratio of spring deflections of primary & secondary
《一九XX年第一季经济报告》
First Quarter Economic Report 19XX
1月第一个周日
The first weekday in January
3根型下颌第一恒磨牙
Permanent three-rooted mandibular first molar