简答题 一块碳质量分数wC=0．1％的碳钢在930℃渗碳，在距表面0．05cm处碳含量达到wC=0．45％。在t＞0的全部时间，渗碳气氛保持表面成分为wC=1％，假设DCγ=2．0×10-5exp（一140000／RT），求：①渗碳时间；②若将渗层加深一倍需要多长时间；③若规定wC=0．3％作为渗碳层厚度的度量，那么在930℃渗碳10h的渗层厚度为870℃渗碳10h的多少倍？

A．Women have a biological bent for depression.
B．The chance for women to have a major depression is twice as high as it is for men.
C．Social double standards are the major cause for women’s depression.
D．More women sought help，and this makes it seem like more women suffer from depression.

A.6
B.12
C.3
D.8