Abstract Expressions like English ago have been claimed to be among the most likely candidates for postposition crosslinguistically, and the reason for this has been conjectured to be diachronic. A few previous contributions notwithstanding, however, we still lack a typologically wider-ranging account of such temporal adpositions and adverbials and of how they develop. These are the main goals of the present article. Relying on a sample of 100 languages, it has been found that: (i) the structure instantiated in English by ago is far from universal and is geographically unevenly distributed; (ii) these expressions are indeed predominantly postposed, which does not hold for their mirror images for the future; and (iii) evidence from etymology, patterns of polysemy, and documented semantic extensions suggests that this asymmetry is the result of past and future markers having different diachronic sources.

中文翻译：

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时间状语和介词的过去未来不对称：跨语言和历时的观点

摘要像英语之前这样的抽象表达被认为是跨语言后置的最有可能的候选词之一，并且其原因被认为是历时性的。尽管有一些先前的贡献，但是，我们仍然缺乏这种时态和副词以及它们如何发展的类型广泛的解释。这些是本文的主要目标。依靠100种语言的样本，我们发现：（i）以前以英语实例化的结构还远未普及，并且在地理上分布不均；（ii）这些表情确实主要是摆在后面的，这对于将来的镜像并不适用；（iii）来自词源学，多义模式的证据，