The findings in the present study provide support for the Comprehensible Output Hypothesis, which claims thatthe activity of producing target language may prompt learners to recognize their linguistic problems.With regard to the language features that the subjects focused attention to in their production, the use of verbscomes first, followed by the use of nouns, articles, participles, prepositions and so on. Those features are alsofound to be problematic in previous research within an EFL setting (Garcia & Pica, 2000), which suggests thatthese grammatical items are the major problems that EFL learners feel difficult to overcome and need greatefforts in their future learning.