—How was your day off yesterday?

—Perfect! It was _____ birthday of my grandma's. We had a big family celebration. [ ]

A. eighty

B. the eightieth

C. eightieth

D. eighties

检查轴密封同心度偏差时，把百分表固定在轴上，触头对准密封腔内孔面回转一圈得到百分表指示的（），即为同心度偏差。

A、最大值与最小值之差

B、最大值与最小值之和的一半

C、最小与最大之差的绝对值

D、最大值与最小值之差的一半