Researches on teacher talk in China start from the thesis “The Investigation and Analysis of Teacher Talk in University English Reading Class” written by Zhao Xiaohong (1998). After that, Chinese researchers (Zhou & Zhou, 2002; Hu, 2003, etc.) made a selection of teacher questions, interactional modification and teacher feedback as their measures to delve into teacher talk in second or foreign language classroom. As theoretical studies, Zhang Min (2002) pointed that teacher talk, as the main language input and teaching medium, has the limitation of form and function, which is disadvantage to the development of learners. Xiao Su (2003), Tang Yanyu and Liu Shaozhong (2003) analyzed the function of teacher talk from the perspective of pragmatics. Later, inspired by foreign researches, China foreign language field began to do some empirical studies about teacher talk. Xu Ying (2003) investigated and analyzed teachers’ polite expressions; Hu Qingqiu (2004) discussed the relationship among teachers’ questioning ways, skills and students’ participation. Zhou Junping (2006) showed that Teachers who improve their discourse quality can create more opportunity for students to join classroom activity and promote their second language acquisition.

2.2 Types of Teacher Verbal Feedback

There is little controversy about the definition of teachers’ feedback. All in all, it is modified as follows: in the English classroom, the response given by teachers to learners’ response behavior, aiming to help guide or motivate the learners during the learning. Teachers’ feedback includes verbal feedback and non-verbal feedback. The present thesis will focus on the verbal feedback, because of a lack of facilities that could record clear videos.