2. Synchronic vs. Diachronic (共时与历时) Language can be studied at a given point in time or over time. When we study language at a particular time, it is called synchronic linguistics. When we study language developments through time, it is called diachronic or historical linguistics. Synchronic linguistics focuses on the state of language at any points in history while diachronic linguistics focuses on the differences in two or more than two states of language over decades or centuries. 语言研究可以是在一个给定的时间也可以是一段时间。当我们集中在某一点时间来研究语言时就叫做共时语言学。当我们研究随着时间发展的语言时就叫做历时语言学。共时语言学集中研究历史任何时期点的语言现状，而历时语言学集中研究几十年或几百年的时期内两个或比两个更多的语言状况的差异。