中文摘要：

本文研究了复杂度为n＋2的序列.利用代换的理论以及词上组合的方法,刻画了这类序列,揭示了它们与Sturmian序列的密切联系.

英文摘要：

In this article,we study sequences of complexity n＋2.By using theories of substitutions and combinations on words,we characterize these sequences that are tightly related to the Sturmian sequences.