In recent years, underground economy has become a burning field of research all over the world.

最近二三十年，地下经济问题逐渐成为国内外学术界的一个研究热点。

Analysis in reality is on tax reason and non-tax reason why underground economy exists in our country.

现实分析主要从我国地下经济产生的非税收原因和税收原因两个方面进行分析。

Because at that time, the underground economy had not displayed the inflation tendency, the research scope was quite limited.

但由于当时地下经济并没有表现出膨胀的趋势，所以研究的范围还是比较有限的。

This thesis is basically concerned with Underground Economy, an area that remains to be fully understood but has attached increasing attention.

本文研究一个还没有被充分认识但日益受到人们关注的经济活动领域——地下经济。

All bloggers know that the way to get links is to engage in the secret underground economy of sucking up to bloggers with higher Technorati rank than you.

所有博客作者都知道，得到链接的方法是参与到吸收拥有比自己更高的Technorati排名的博客作者的神秘地下系统中。