「了」為中文常見的時貌標記和句尾虛詞，但其表動作完成的語義，可能使華語學習者將其泛化為過去時標記，而成為學習難點。本文以「臺師大華語學習者語料庫」為本，分析初級 A2和中級 B1英語母語者學習「了」字句時的使用情形和偏誤類型，有以下幾點發現：（ 1）初級 A2和中級 B1學習者都較難掌握作為時貌標記的「了 1」，而較容易掌握作為句尾虛詞的「了 2」。（2）不論初級 A2或中級 B1都有「了 1」過度泛化的情況。（3）此二級學習者在「了 2」及「了 1+2」的使用上，皆多為冗餘偏誤。對於「了」字句的教學，本文與鄧守信（ 1999）所主張的建議一致，「了」字句之教學上可由簡入繁，先介紹「了 2」和相關句型，再介紹「了 1」和相關句型。同時，本文亦歸納出「了」字句教學時應釐清的重要觀念和建議的教學順序，期能提供華語教材編寫的參考方向。

The function word “le” in Chinese serves as both a sentence final particle (le1) and an aspect marker (le2). As an aspect marker indicating the completion of action, “le” has been observed to be frequently misused by learners of Chinese, among which the overgeneralization of “le” a past-tense marker is the most glaring. Based on “NTNU Chinese learners’ written corpus”, we analyzed the usage and the error types of “le” made by English-speaking learners at the beginning (A2) and the intermediate level (B1).The results show that both A2 and B1 learners acquire le2 before le1, and in terms of error analyses, le1 is the most commonly spotted error type and there is a large number of redundancy of the use of le2 and le(1+2). Therefore, in a similar vein with Teng (1999), this current study sides with the proposition that the use of le2 along with its associated sentence patterns should be taught prior to that of le1. Pedagogical implication as well as the suggestion of the editing of CFL textbooks are also provided.