本文讨论单个函数的平移和伸缩的组合在Ｓｏｂｏｌｅｖ空间Ｗ２Ｍ（Ｒｎ）中稠密的问题，得到了稠密的一个充分必要条件，并对于Ｗ２ｍ（Ｒｎ）中紧集内的函数给出更强的逼近结果。

In this paper, we investigate denseness of superposition of one functionwith its translation and dilation in Sobolev space W2m(Rn), and give a necessary andsufficient condition for denseness. Furthermore, we obtain a strong aproximate resultto the functions in any compact set of W2m(Rn).