Mr Wang was born June 15th, 1977 Hefei. [ ]
A. on; in
B. in; in
C. in; on
D. on; on
答案:A
已知一轧件(管)的断面积为Fo,轧制结束后成品的断面积为Fn,其中Fo=0.025m2,Fn=0.0052m2,计算其总延伸系数是多少?