本文探討漢語使役動詞成為條件連詞的雙線發展：一線從命令義使役動詞虛化為條件連詞，文中以「使」和「令」的歷史發展為例說明；另一線從任由義使役動詞虛化為讓步條件連詞，文中以「饒」和「任」的歷史發展為例說明。本文第一部分側重這兩線發展的演變過程、條件和機制，並主張第一線是由代喻機制促成，第二線則是由隱喻機制促成。文中還透過比較指出早期使役條件句帶有「背離事實」的特性，而早期使役讓步條件句則帶有「凸顯對比」的特性。本文第二部分則進行跨語言比較。首先舉出希臘語as的平行發展，顯示上述兩線發展並非漢語所獨有，而是具有普遍性，且Nikiforidou （1996）所提as虛化的演變條件和演變機制也印證本文的分析。最後指出，使役動詞這兩線發展呈現從「意合連結」（parataxis）到「形合連結」（hypotaxis）的轉變，呼應Hopper and Traugott（2003 [1993]）所主張的子句連結漸變過程。

This paper discusses the grammatical transformation of Chinese Shi-yi verbs into both conditional conjunctions and concessive conditional conjunctions, which are respectively exemplified by the historical developments of the requesting verbs shi (使) and ling (令) and the letting verbs rao (饒) and ren (任). The first part of this paper focuses on the processes, conditions and mechanisms for the two paths of grammatical transformation. It argues that the mechanism for the first grammatical transformation is metonymy, whereas the second is metaphor. By comparison with other conditionals and concessive conditionals, this paper also demonstrates that the conditionals derived from Shi-yi constructions have the characteristic of being “counterfactual,” whereas the concessive conditionals derived from Shi-yi constructions have the characteristic of being “contrastive.” The second part of this paper focuses on cross-linguistic comparison. The parallel development of the Greek as is introduced to show that the grammaticalization discussed in this paper is not unique to Chinese. The conditions and mechanisms of the grammaticalization of as proposed by Nikiforidou (1996) can also be used to support the analysis in this paper. Finally, this paper points out that the two paths of grammaticalization are from parataxis to hypotaxis, similar to the cline of clause-combining constructions proposed by Hopper and Traugott (2003 [1993]).