【Abstract】Monitor model consists of five related hypotheses；especially， input hypothesis or （“i+1” theory） is regarded as the core of Krashens theory.The purpose of this thesis is to enable learners and teachers to deeply understand of input hypothesis， so as to raise learners learning efficiency and language teaching quality.

【Key words】Krashen； second language acquisition； input hypothesis

1. Introduction

Background of the Present Study

Krashens theory makes a potential impact on language teaching， although there are criticisms on input hypothesis. The input hypothesis （i+1） better known nowadays as the comprehensible input. Many scholars notice that the success in foreign language teaching depends on input factor. Such as， Eills， Skehan， Zhang Huping （Zou， 2000）. They hold that if input hypothesis base on some conditions， acquisition will take place. First， providing comprehensible input；Second， language input will involve in learners current state of knowledge （i） and higher above the learners level （i +1）. Meanwhile， some scholars revealed that this theory has little meaningful guidance in real application.

2. Theoretical Basis of Input Hypothesis

2.1 The Silent period

Krashen （1982） states， input hypothesis consistent with some findings in second language acquisition. According to Krashen， Silent period means L2 learners have acquired L1 and know about knowledge but they refuse to speak for a certain period. During this period， a child is building up competence in SLA through listening. Sufficient competence has been developed by listening and understanding

2.2 Interrelated Five Hypotheses

Krashen emphasize the differences of acquisition and learning. He noticed acquisition refers to implicit， informal， and picking up a language. Learning refers to the conscious study of a second language（Krashen， 1982）；According to Krashen （1982） if children first acquire English as his native language， they will tent to firstly acquire grammatical structures morphemes， or functions word；The Monitor Hypothesis affirms the learned knowledge has a special function. It severs as a monitor.speak or write；The Input Hypothesis is the core of Krashens SLA theories. It states that acquisition takes place because the learners having understood input （i+1） that is a little higher the current level of learners competence；Affective-Filter Hypothesis：Krashen （1982） holds a variety of affective factors （motivation， self-confidence， anxiety） relate to success in second language acquisition.endprint

3. Understanding of Input Hypothesis

3.1 Definitions of Input

Eills （1999） defines that input is used to refer to the language that the learner is exposed. It can be spoken or written. According to Longman Dictionary （2000）， Input refers to in language learning which a learner hears or receives and from which he or she can learn. Actually， output is based on input， without input there is no output.

3.2 The Importance of Comprehensible Input for Learner

According to Krashens theory （i+1）， the concept of comprehensible refers to input language which include linguistic items that are slightly higher than the learners current language competence. Adult usually need to modified and adjust their speech when talking with little child. These special speeches known as “motherese”， “caretaker talk”. Meanwhile， teachers speak to L2 learners in special ways. Teachers also act the role of modified their speech to learners competence level.

3.3 The Limitations of Input Hypothesis for Language Teaching

The theory of “i + 1”， acquisition only takes place in real setting and naturalistic communication. Krashen advocates natural input， so teacher should take “here and now” principle into consideration. Second language acquisition takes place when learners are contacted with sufficient and comprehensible input. SLA is affected by learners individual difference such as age， learning style， aptitude， motivation， cognitive style and personal trails. Teacher cant know the current level of all English learners.

4. Conclusion

Draw a conclusion to the discussion on Krashens theory. The author find out that there are limitations on input hypothesis. It is impossible for teacher to verify what comprehensible input actually consists of. However， it remains true that Krashens theory have highly influential in shaping language teaching.

References：

[1]Eills，R.Understanding Second Language Acquisition.（1999）.Oxord：Oxord University Press.

[2]Krashen，S.D.Principles and Practice in Second Language Acquisition.（1982）.New York：Pergamon Press.

[3]荊增林.對(duì)克拉申輸入說的異議[J].外語教學(xué)與研究，1991，85 （1）：53-56.

[4]鄒為誠.語言輸入的機(jī)會(huì)和條件[J].外語界，2000，77（1）：1-8.

作者簡(jiǎn)介：袁依諾，沈陽師范大學(xué)，大學(xué)外語教學(xué)部，課程與教學(xué)論（英語）研究生。endprint