本研究旨在探討以中文為母語的學生對英語條件句之第二語言習得，主要的議題包括是否有第一語言轉移（L1 transfer）的現象、難易順序、題型效應、組別效應以及英語能力對此結構習得的影響。本研究為實證性研究，採用兩個實驗題型：文法判斷題與引導式翻譯題；試題以單句和情境式對話呈現。受試者為六十位以中文為母語的大一學生，依據其英語程度，分為初、中、高三組。實驗結果顯示，受試者在表達英語條件句時，的確受到第一語言轉移以及第二語言複雜度的影響。其中，初階學習者在條件句表達中有較多受母語影響的錯誤，隨著英語能力的增加，此類型錯誤大幅降低，轉為受第二語影響的錯誤。根據受試者的表現，在七種條件句中，預測條件句（predictive conditional）表現最好，最易習得；受試者感到最困難的是未來假設條件句（future hypothetical conditional）以及時態混合型反事實條件句（mixed-time-reference counterfactual conditional）。此外，研究亦發現，受試者習得英語條件句時，確實受第一語言轉移以及第二語言複雜度之影響。在題型效應方面，受試者在文法判斷題的表現比引導式翻譯題好，顯示此結構之理解優先於其表達；然而，受試者在單句和情境式對話中的表現無顯著差異。最後，在組別效應方面，三組受試者對英語條件句的表現有顯著差異，顯示受試者對於條件句的習得會隨著英語能力的提升而改善。
In second language acquisition, English conditionals are regarded as one of the most difficult constructions (Covitt 1976). However, little research has conducted an empirical study on the competence and performance of Chinese EFL learners' acquisition on conditional sentences. Therefore, the present study aims to investigate Chinese EFL learners' acquisition of English if-conditionals with two tasks (a grammaticality judgment task and an elicited translation task) in different formats (in isolation and in context). Factors such as L1 transfer and L2 proficiency were examined. The subjects were sixty college freshmen in Taiwan, and they were further divided into three groups according to their English proficiency levels. The results show that the seven conditional types examined in the study exhibited different degrees of difficulty. The predictive conditional was found the easiest, followed by the present hypothetical and present counterfactual conditionals. In addition, the past counterfactual and the factual conditional were found challenging and the future hypothetical and mixed-timed-reference counterfactual conditionals were the most difficult to acquire. Syntactic and semantic complexity along with L1 transfer accounted for the subjects' developmental patterns. As for the task effects, the subjects performed better on the comprehension task than on the production task, but their performances on test items with contextual cues were not significantly different from those without cues. Finally, the present findings indicate that the subjects at higher L2 proficiency levels did perform better than the lower proficiency groups.