第一第二系弹簧挠度比
ratio of spring deflections of primary & secondary
列作第一组别学生
were ranked as band one students
《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
I-fuzzy第一可数性
I-fuzzy First-countability