Secondly, it is about the studies on the language functions of CI。 The transmission of instructions has many language functions。 Hughes (1993) held the opinion that the most important functions are: 1) commands, 2) requests and 3) suggestions。 He dedicated that the use of “command” stressed the authority of teachers。 “Request” expressed the conception of equality in the class。 “Suggestion” gave students more free choices of selection。 Based on the speech act theory, Tang Yanyu and Liu Shaozhong (2003) analyzed the language functions of CI。 In their opinions, the purpose of instruction is that the teachers as speakers ask students as listeners to do something, to change reality, to finish one task or to make a product。 It is the same as the conception “do things with words” in the speech art theory。 Liu Xiaolin (2008) proposed CI has four kinds of functions as followings by doing classroom observation: simple instructions, instructions with explanation, repetitive instructions with emphasis and instructions with check-up。 She explained these four in her thesis。 Simple instructions mean the instructions are clear and brief, easy to express。 Instructions with explanation mean there is necessary explanation after giving instructions to make them clearer。 Repetitive instructions with emphasis mean teachers use repetition to stress some important information in the CI。 Instructions with check-up mean to add some simple question after giving instruction to check if students understand them well。 In a word, there are fewer studies on the language functions of CI both at home and abroad。 But the researches on this aspect based on the speech act theory will play an important role in the EFL classroom。 

To sum up, many west scholars have emphasized on the guidelines of how to give effective CI (Ur, 1996; Parrott, 1993; Hanner, 1998)。 Huges (1993) studied CI from the perspective of functions。 Tsui studied it from the view of speech act theory。 Chinese researchers also got some results。 Zhu Donghua (2002) dedicated the reason of giving ineffective CI。 He Anping (2003) researched the conceptions hidden in the CI。 Liu Xiaolin (2008) classified CI and gave it a clear definition。 As we can see there is increasing attention and studies towards CI。 More studies are also needed in the future。 

2。3 Input modifications of TT。

It is widely known that teacher will change their ways of giving instructions in order that students can have a better understanding in the EFL classrooms。 The researches on the adjustments of teacher talk are also helpful to the studies of CI since CI is included in TT。 So in this part the studies of TT will be discussed。 Based on this it is necessary to study what strategies will be taken in order that students can understand CI better in the class of EES in Zhejiang province。 

2。3。1 The effect of temporal variables

A。 Pause 

One way to make students get better understanding of CI is to adjust the temporal variables like pause and rate。 Pauses are used at the boundary of two sentences, which may be just a natural marker of slower speech。 Brown and Yule (1983) assumed that extended and long pauses might be proposed as unit boundaries, whereas the short pauses might be treated as unit-internal。

Pauses can be used to make a slower speech。 It can also be designed for comprehension because teachers spend some extra time to make a better plan of their speeches to satisfy the students' need。 And the number and duration of pauses used by a speaker will obviously vary according to his rate of speech (Chaudron, 1988)。  Blau (1990) did an empirical study on the effect of syntax, speed and pauses on listening comprehension with the 72 first-year English institute students at a university in Poland and 100 students who take English as a second language course at a university in Puerto Rico。 It can be seen from the result that speech with pauses is always easier to understand while the mechanical slowed one is the least comprehensible。