rors are one of the most frequent error types in learner English (Tetreault and Chodorow, 2008); (b) they are relatively explainable (c.f., article errors); and (c) it would be a good starting point for feedback comment generation research considering the potential difficulty of the task.
we have annotated learner corpora with feedback comments, written in English and Japanese, on preposition use; we have released a part of the dataset to the public.