The purpose of this study is to examine the use of words and fixed expressions by intermediate- level EFL learners through the analysis of learner corpora. Previous studies have revealed that second language learners of English (NNS) used a wide variety of fixed expressions in the same manner as native speakers (NS). However, their types were different from NS, and some phrases were either overused or underused. There are many cross-sectional learner corpus research studies, but few studies on longitudinal design have so far been conducted. In the present study, I would like to analyze a new longitudinal corpus, which consists of writing data compiled by 89 intermediate-level EFL learners.

To conduct the present study, three corpora were used: one is the corpus of writing in which the topic was “violence scenes on TV programs" by intermediate learners (Week 2 Corpus); the second consisted of writing in which the topic was “school education" by the same learners (Week 15 Corpus); and the third was NICE-NNS, which is part of the Nagoya Interlanguage Corpus of English and consists of the writing data of advanced learners. From each corpus, the N-gram expressions were extracted, and I analyzed the similarities and differences between them.

The results showed that some fixed expressions were changed throughout the four months of classroom instructions. In Week 2 Corpus, the phrase “I think" was frequently used throughout the instruction; the frequency of “I think that" was reduced, and instead, “It seems that" was used. In comparison to NICE-NNS, the types of expressions used were different, and advanced learners tended to use a greater variety of fixed expressions and prepositions than intermediate learners.