Learning has the function of monitoring and editing the utterances produced through the acquisition process. The acquired system acts to initiate the speaker‘s utterances and is responsible for fluency and intuitive judgments about correctness, whereas the learned system acts only as a monitor, making minor changes and polishing what the acquired system has produced. Monitor model has been very influential in supporting communicative language teaching, which focuses on using language for meaningful interaction and for accomplishing tasks, rather than on learning rules.