2。1。4 Questioning

Holland, R。 & T。 Shortall (1997) found that much of teacher’s talk in the class refers to questions and Mc Donough (1993) explained that question may stimulate learners to develop linguistic competence。 Richards and Lockhart (1996) also spoke high of teacher’s questions, which take an indispensable role in learners’ second language acquisition。

Quantities of researchers devoted to defining different types of questioning and constructing respective taxonomies to separate questions。 Barnes (1969) pided questions into open question and close question, while Ellis (1994) discussed the difference between referential question and display question。 One framework formulated by Long and Sato (1983) contains Echoic types, with comprehension checks, confirmation checks and clarification requests included, and Epistemic types, with rhetorical, expressive, referential and display involved。 Richards and Lockhart (1996) indicated that the taxonomy of question consisted of procedural question, convergent question and pergent question。 

The research (Long & Sato 1983) showed that under authentic teaching circumstance teacher provided much more display question than referential question。 The fact aroused great concerned of some linguists who had a preference for referential question。 Brumfit (1990) revealed that referential question may increase learners’ output on target language。 Brock (1986) and Nunan (1987) both stated that referential question which requires learners to make a more complex response may facilitate learners’ language acquisition to a greater extent。

2。1。5 Feedback

Feedback is a teacher’s response to learners’ output, which in Ellis’s perspective (1985) may help to verify hypotheses of target language rules。 Tusi (1985) stated that positive feedback is a supportive evaluation on students’ performance and negative feedback is teacher’s correction on students’ errors。 Richards & Lockhart (1994) proposed three purposes of teacher’s positive feedback: first, to affirm students’ correct performance; second, to praise and encourage the respondent; and third, to build a harmony atmosphere for later teaching activities。 Ellis (1990) illustrated that positive feedback stimulates learners’ motivation on language learning and negative feedback may frustrate students' enthusiasm, so teacher would better adopt positive feedback as much as possible and abandon the negative feedback。 But Chaudron (1986: 66) insisted that “Error is generally defined with reference to the production of a linguistic form which deviates from the correct form”。 Long (1996) agreed that negative feedback actually reminds learners of incorrect and incomplete inter-language and guides learners to modify language production, which at last contributes to target language acquisition。

2。2 Classroom interaction hypothesis

2。2。1 Krashen's Comprehensible Input Hypothesis

The Input Hypothesis proposed by Stephen Krashen (1978) states that acquisition happens only when there is input and this input has to be comprehensible or the completion of “I+1”, in which “I” represents learner’s original linguistic competence and “1” symbolizes the new language knowledge which learner attempts to command through teacher’s input。 “If input is understood, and there is enough of it, the necessary grammar is automatically provided。 The language teacher thus needs not attempt deliberately to teach the next structure along the natural order- it will be provided in just the right quantities and automatically reviewed if the student receives a sufficient amount of comprehensible input” (Krashen 1985:2)。 According to Krashen's Comprehensible Input Hypothesis, teacher talk is quite significant as a resource which helps students to achieve the SLA (Nunan 1991)。