有符号的

A sufficient condition for supersolvable group depending on theproperty π-quasinormal of its Fitting subgroup is given.

聂林通过讨论有限群的Fitting子群的极小子群的π-拟正规性，利用有限群的正规群列及多种有限群论的方法和技巧，得到了一个有限的可解群成为超可解的充分条件。

This paper points out main disadvantages of mining technology being used in small collieries and discusses how to adopt long room system to reform the current technology of mining.

论述了目前小煤矿开采技术存在的主要问题，探讨了采用长房式采煤法改革小煤矿开采的技术问题，此法适用于条件合适的小煤矿。