本論文旨在探討焦點詞的句法結構，並探索台灣JFL學習者習得焦點詞的過程。
焦點詞的語義功能，是針對句中命題的某一成分加以聚焦，並彰顯此一命題與另一個句子中相關命題之縱聚合關係。本論文以「日本語記述文法」(2009, 2010)、益岡(2007) 與沼田(2009) 為理論基礎，針對焦點詞的句法結構進行深入的探討。在習得研究方面，則以LARP作文語料庫中，8位學習者歷經3年半所寫33篇作文之初稿，以及針對初稿所作之後續訪談為研究對象，探究學習者焦點詞的習得過程。本研究之結論可歸納如下：
1. 句子的組成單位可分為詞、詞組、子句3種，而在「語義－句構」的架構上，句子可分為命題與情態兩大部分。詞、詞組、子句同時也是命題
的構成成分。
2. 焦點詞可出現在命題中詞、詞組、子句任一成分之後。日語是「主要語在後」的語言類型，因此「○○＋焦點詞」的結構可以視為是「焦點結
構」。該結構可以「F-con：X＋F」表示; X代表詞、詞組、子句等聚焦成分，F則代表焦點詞。
3. 原則上，焦點詞出現在聚焦成分之後，但是「主格・受格・與格」以及「後置詞詞組」受聚焦時，則呈現「兩階段操作」模式。因為該兩種詞
組的結構是「NP＋格助詞」，所以焦點詞可以出現在 ① NP之後或 ② 格助詞之後。
4. 最容易習得的焦點詞是「は／も1／だけ」，習得困難的焦點詞是「のみ／など2／なんて1／なんて2／でも／さえ2／だって」;而「など1／ばか
り／しか／も2／くらい／こそ／まで／さえ1」介於兩者之間，「すら」則沒有被使用。焦點詞的習得順位、使用次數、習得難易三者間有密切的
關聯。
5. 最容易成為聚焦成分的是NP，而「述語VP＋F」的進展順序，則是「V-(r) u＋F」→「V-te＋F＋いる」與「V-(i)＋F＋する」。
6. 半數以上的聚焦成分在第1期就已陸續出現，這顯示教室習得有助於学習者，在短期內有系統且快速地習得並且運用相當多的句法形式。
本論文共分6章。第1章「序論」，說明本論文的研究目的、研究方法與論文結構。第2章「前人文獻」，整理了宮田(1948) 等學者的學理。第3章「焦點詞的句法結構分析」，分析了日文的句構成分以及焦點詞在句中的位置。第4章「從學習者的書寫表達看焦點詞的習得過程―縱斷的研究【研究1】」與第5章「從學習者的口語表達看焦點詞的習得過程―縱斷的研究【研究2】」，探究學習者焦點詞的習得過程。第6章「結論」，爲研究結果做總結，並陳述本研究的意義與未來的研究課題。

In writing this dissertation, I have aimed to explore the syntactic structure of focus particles and identify how Taiwan’s JFL students acquire Japanese focus particles. The semantic functions of focus particles are to focus a certain component of the proposition of a sentence and to highlight the paradigmatic relationship between this proposition and another relevant proposition of another sentence. This paper, based on the theory in Japanese Descriptive Grammar (2009, 2010) as well as those proposed in Masuoka (2007) and Numata (2009), offers an in-depth look at the syntactic structure of Japanese focus articles.
In the area of language acquisition, I have, drawing upon the LARP Corpus, attempted to discover how students absorb focus particles. The materials used in this research are the first drafts of 33 essays written by eight learners over a period of three and a half years, as well as the results of follow-up interviews conducted on the basis of these essays.
The main points of this paper can be summarized as follows:
1. The three kinds of components that constitute a sentence are words, phrases and clauses. Considered
from a “semantic-syntactic” viewpoint, a sentence has two aspects: proposition and modality. Words,
phrases and clauses are also the components that constitute the proposition.
2. A focus particle can follow a word, phrase, or clause in a sentence. Japanese is a “head-final”
language; therefore, the “○○+ focus particle” construction of the language can be regarded as a
“focus construction.” This construction can be denoted by “F-con: X＋F, ” where X may be a word,
phrase or clause, and F is the focus particle.
3. In general, the focus particle follows the focus element; however, when the “subjective
case/objective case/dative case” and the “postpositional phrase” are focused, this happens on a
“two-stage” model, because the construction of these two kinds of elements appears as “NP +
particle. ” Accordingly, the focus particle follows either the NP or the particle.
4. The focus words most easily acquired are “wa, mo1, and dake” while those which are hard to learn are
“nomi, nado2, nante1, nante2, demo, sae2, and datte. ” Those in between are “nado1, bakari, shika,
mo2, kurai, koso, made, and sae1, ” while “sura” is not used. There is a correlation between the
order of acquisition, the frequency of use, and the degree of difficulty of the particles.
5. The element that is most frequently focused is NP. As for the development of the form of “predicate
VP＋F,” it goes as “V-(r) u＋F” → “V-te＋F＋iru” as well as “V-(i)＋F＋suru.”
6. The majority of the focus elements emerge in students’ use of Japanese during phase 1. This
indicates that learning which takes place in the classroom contributes to systematic and prompt
acquisition of a large number of syntactical elements.
This dissertation is divided into six chapters. The first chapter, “The Preface,” states the purpose of the study, the methods adopted for conducting the study, and the main points covered. The second chapter, “Relevant Literature,” summarizes the related theories formulated by scholars such as Miyada (1948). The third chapter, “An Analysis of the Syntactical Structure of Focus Particles,” looks at the syntactical components of Japanese and the positions of focus particles in Japanese sentences. The fourth and fifth chapters, “On the Acquisition of Focus Particles by Taiwanese JFL Learners Through Writing—A Longitudinal Study (Study 1)” and “On the Acquisition of Focal Particles by Taiwanese JFL Learners Through Oral Communication—A Longitudinal Study (Study 2) respectively, describe how Japanese learners in Taiwan acquire focus particles. The last chapter, “Principal Conclusions,” summarizes the results of my research while pointing out the significance of this study and stating relevant topics I will research in the future.