摘要：Previous accounts show that markings of CF (counterfactual) clauses tend to be complex. One frequent combination of markers that shows up in many languages is that of a past tense together with perfect in past CFs. According to Dahl (1997), the stacking use of CF markings consists of elements of varying historical layers. This motivates a closer look at the diachronic history of each marking in the combinations that do occur. This paper is therefore devoted to a diachronic development of CF markings. A diachronic study of frequently used CF markers such as past tense, perfective/imperfective aspect, irrealis mood markers is conducted. I propose a cross-linguistic whole life-cycle of CF markers which start as pragmatic clues, termed as CFEnhancing (Counterfactual Enhancing) markers in this paper. The following part will address the question concerning the origins of counterfactuality ahead of the main discussion.
