The function of language teaching is self-evident in our second language acquisition.Teachers and students are two important participants who play the most important role.When we have a clear understanding of their respective roles， and then analyze the other functions based on experience， this will give us a clearer indication of the role of language teaching.

In terms of the process of foreign language teaching and learning， a teacher should be defined as a initiator of knowledge， a presenter of skills， and a person sharing resources.At the same time， teachers should play different roles according to different teaching objectives and scenes to get the desired teaching results.

First of all， as a initiator of knowledge， the teacher should have sufficient knowledge reserve and some skillful teaching methods， and pay attention to the expansion of knowledge and the transmission of emotion in the process of explanation.As what Richards， J.C .（2002， pp19-25） claims in his book： “A good teacher is a person who assesses the needs and possibilities of a situation and creates and uses practices that have promise for that situation.”

Secondly， as a demonstrator of skills， teachers should be proficient in teaching skills and have a clear understanding of skills， such as whether this skill is suitable for curriculum content， whether this skill is within the scope of students acceptance.Additionally， when teachers show their students skills， they should not only let them learn to think， but also let them experience the skills by themselves.At this time the teacher not only as a demonstrator of skills， but also a guide.

Finally， as a resource provider， teachers should keep pace with the times and grasp the latest information， so as to ensure that their resource sharing will not be eliminated by students. At the same time， with the rapid development of the information age， the information of the network is too rich， which lead teachers to choose information with a critical thinking to select resources suitable for their students.

In foreign language teaching， the role of learners， I think， can be divided into two aspects， one is the role of learners on their own learning， the other is the role of learners in the teaching process. As what Brown，H.D （2007，p.70） claims in his book： “We began to encourage learners to ‘take charge of their own learning and to chart their own pathways to success” （Brown， 1989， 2002b； Benson， 2003）. Learners should be responsible for their own learning， and begin to learn to manage and plan their own learning. Through continuous self-learning， they can find their own problems.On the other hand， learners also play an effective role in promoting the whole teaching process， through the observation of the learners and some problems reflected by the learners themselves， the teacher adjusts the teaching plan in time to obtain an ideal teaching effect.

In addition， according to the actual second language teaching experience， the role of language teaching is reflected in several other aspects.First， to promote externalization. In my opinion， the most important role of language teaching is to encourage learners to externalize their knowledge， in other words， to apply what they have learned in practice.Second， supervision and improvement. From a certain point of view， language teaching belongs to a feedback system. Through complete language teaching， both teachers and students can supervise their own teaching and learning process and improve it through subsequent reflection.Third， extension. In the process of second language acquisition （SLA）， both students and teachers， through language teaching， are involuntarily engaged in knowledge and assimilation of the corresponding L2 culture， which is not only effective for L2 acquisition. It also extends their cultural views and world views.

Therefore， in the process of second language acquisition， we must dynamically look at the role of language teaching， just like coin has two sides， as long as we make good use of its advantages， our second language acquisition process will become more smooth.

References：

[1]Richards，J.C.Theories of teaching in language teaching.In J.C.Richards & W.A.Renandya （eds），Methodology in language teaching：An anthology of current practice[M].Cambridge：Cambridge University Press，2002：19-25.

[2]Brown，H.D.Teaching by principles （Chapter 4），Intrinsic motivation in the classroom （Chapter 5），2007.

【作者簡介】曲喆，北京建筑大學。