In this paper, some limit behaviours of two kinds of special dependent random variables are investigated. It divides two chapters. In chapter one, we discuss the limit behaviour of a kind of symmetric random variables sequences, mainly including the strong law of large numbers, the convergence rates of tail probabilities in the law of large numbers and the convergence rates of tail probabilities in the law of large numbers with random index. The results obtained extand some results of classical limit theory under the independent situation. By employing De Finetti theorem, in chapter two we discuss the limit behaviour of interchangeable random variables squences, mainly including the convergence rates in the central limit theorem and the law of the iterated logarithm. |