【摘要】 本文在文献[2]的基础上证明了二元无穷可微函数类C{M_n}_D（?）C{A_n}_D 的充要条件是(M_n^?)（?）1/n=0(A_n^1/n)或(M_n^?)^1/n=O((A_n^?)^1/n);C{M_n}（?）仁C{A_n}（?）的充要条件是（M_n）^1/n=O(A_n^1/n)或（M_n^f）^1/n=O（A_n^f）,从而把一元情况的结论（[1]6.7）推广到二元情况。更多还原

【Abstract】 In this article,we give out the theorem as follow{Mn},{An}aresequences of positive number,D is a open region(a,b)x(c,d),thenif and only ifA Here,C{Mn}s is the class of indefinitely differentiftble function of two variables on S,更多还原