§1引言众所周知,《概率论》中随机变数的分布函数是处处左半连续的。显然,函数的处处左半连续性只是处处连续性的必要条件但不充分。人们自然地要问:什么类型的左半连续性才是连续性的必要而且充分的条件?本文内容之一就在于回答了此一问题,即有 § 1 Introduction It is well known that the distribution function of random variables in Probability theory is left semi-continuous everywhere. Obviously, the left-half continuity of the function everywhere is only necessary but not sufficient for continuity. It is natural to ask: what type of left-half continuity is necessary and sufficient for continuity? One of the aspects of this article is to answer the question of