【正文】It’s generally agreed that teachers of English should use as much English as they can in class. However， it doesn’t mean that Chinese should be completely avoided. On the contrary， Chinese， if properly employed， can help students understand English better. This is based on the fact that they do not acquire English from scratch， but learning English with Chinese as its foundation. Learning is impossible without understanding and if the language used in class is not understandable it is nothing more than some disordered code which is meaningless to learning. Therefore understanding is the premise for language generation and output. The understanding of a foreign language is based on the knowledge and experience of one’s mother tongue. As students may still lack of English knowledge and still have difficulty in understanding what is explained in English， Chinese， therefore， becomes an indispensable tool in an English class. Teachers of English can at least employ Chinese to a） illustrate the place of articulation， b） explain meanings of some abstract
　　words and expressions， c） clarify different language points and d） check students’ level of comprehension. In this way， the time can be saved to carry out other classroom activities. Of course， teachers should always bear it in mind that Chinese should only be used when necessary and they should try their best to create an English setting for the students so that the students can have more exposure to English during the limited time in class.
　　1.Positive effect on the Study of phonetics：
　　The Chinese and English pronunciation are all composed by syllable， pinyin divided into the initial consonant of a syllable and a vowel，which consist of single vowels and compound vowels. English are generally divided into vowels and consonants，Vowels have unit notes and double vowels.Initials in Chinese is equivalent to the consonants at the beginning of syllable in English， a vowelis equivalent to a vowel in English.Initials and consonants have many similar place in pronunciation parts and methods.So most people can sound the following phonemes without obstacles： ：/p/、/b/、/t/、/d/、/k/、/g/and/f/，for a corresponding in Chinese p、b、t、d、k、g、and f.vowel phonemes /i：/、/u：/and/a：/，can also found the corresponding phonemes in Chinesei、u、and a.Therefore by comparing the similarities and differences between pronunciations can master the correct pronunciation in foreign language learning.
　　2.Positive effect on vocabulary：
　　Use mother tongue interpretforeign language directly：Students already have a certain amount of native language background knowledge and cognitive understanding ability in their mind when study foreign language.So we can use Chinese to explaining abstract words horizon（地平线）， parliament（议会），sociology（社会学），it will receive twice the result with half the effort when adding mother tongue in teaching. It might be hardly to make it clear if we totally use English to explain. Some words such as specific things， time， location and space： school（学校）、second（秒）、star（星星）、moon（月亮）、book（书）、water（水），can use mother tongue to explaining them directly. Because those things and concept has been formed in our mind， we just need to teach a new symbol and expressing forms.It can clearly be seen that it is not only strengthen the understanding of these words， but also save a lot of time to undertake other teaching activities.
　　To explain word-formation in English：Chinese has many meaningful characters，
　　such as 树、材 、森are all relevant with 木，it is similar to prefix notation and postfix notation in English. Therefore you can linked these prefixes and postfixes together to remember， such as bi-（double）、vice-（deputy）、pre-（before）and-less（with-out） etc.It can help students easily understand and remember.And other words would got a different meaning with root after pulsing affix， such as indifferent（冷漠的）has totally break away from root ，different（不同的）；respectful（有礼貌的，尊重他人的）， respective（各自的）； consider（考虑），considerate（体贴的）.Teacher may use mother tongue to facilitate students’ memorization and mastery of characters.
　　3.Positive effect on the study of grammar：
　　Although English and Chinese are not same， but their sentence patterns are still have some similarities：
　　1.S+V eg.Mum is cooking.妈妈正在做饭。
　　2.S+V+O eg.The little girl broke a cup.小女孩打碎了一只杯子。
　　3.S+V+P eg.My brother is a doctor.我哥哥是个医生。
　　In Chinese， Compound sentences or complex sentences with clause are similar to English： 
　　If you feel sleepy，you’d better go to bed now.如果你感觉困了，最好现在就上床睡觉。
　　She is the kind of people who is always prepare to help others.她是那种随时准备帮助别人的人。
　　This is the reason why he was punished by the law.这就是他为什么会受到法律 惩罚的原因。
　　As a kind of knowledge， mother tongue is stably. when it is similar with the target language， acquirers can learn faster in these areas. The native language knowledge and skills of learners are far from negative effect or interference， but play a positive role in promoting. The research behind shows that mother tongue is a exploited resource， and it can help learners to comb the obtained language input and make the language use at highest level. Due to mother tongue has a positive effect on phonetics， vocabulary and grammar，the teaching effect can greatly changing better by playing essential role of mother tongue. Finally， mother tongue can accelerate the acquisition process of target language.
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