【Abstract】The paper， based on language acquisition theories， discusses their similarities and differences from comparing children’s L1 acquisition and adults’ second language acquisition， and derives some implications for EFL education.
　　【Key words】Children’s L1 acquisition； adults’ SLA， similarities； difference； implications.
　　【作者簡介】江苗（1987-），女，汉族，江西赣州人，广州南洋理工职业学院外国语学院，硕士，讲师，研究方向：英语教学，应用语言学。
　　1. Introduction
　　Numerous evidences show that children’s first language （L1） acquisition is effortless and successful mostly， but adults’ second language acquisition （SLA） painful and turn out to lack of success in most cases. Therefore， the field of children’s L1 acquisition gains much interest of linguists in SLA research and EFL teachers. The research on children’s L1 acquisition has profound influence in the SLA. It can be a starting point for us to improve English teaching and learning. This paper mainly discusses similarities and differences between children’s L1 acquisition and adults’ SLA， and derives some implications from the discussion.
　　2. Similarities
　　2.1 Development Patterns
　　Children’s L1 acquisition and adults’ SLA may go through similar stages. The development patterns—silent period， formulaic speech and structural and semantic simplification， bear resemblances （Ellis， 1994）. A silent period is necessary for children and adults， and structural and semantic simplification appear both in Children’s L1 acquisition and adults’ SLA at the early development stages. Although there are many variables in different learners in L1 acquisition， for example， the rapidity of language development， overall， children has a silent period in which they experience the rules and use of a language via listening before they start to produce complete utterances.
　　Both native speakers and second language acquirers produce Formulaic speeches at the early stages. It is the whole utterances learnt as “memorized chunks”， e.g. “I hope so” or“partially unanalyzed utterances with one or more open slots”， e.g. “would like to ____？”（Ellis，1999）. Structural and semantic simplification takes place in both. Articles， auxiliary verbs and the suffixs like –es， -ed are usually removed in simplified structures. And “content words—nouns， verbs， adjective and adverbs” usually are removed in simplified semantic （p.89）
　　For example： school = She is at school.
　　go？ = Shall we go？
　　So first language acquirers and second language acquirers share the similar development pattern. 　　2.2 Natural order
　　Some similarities can be found in sequence of children’s L1 acquisition and adults’ SLA. The natural order of them can be predicted. The acquisitions of bound morphemes， or factors are earlier than others in both. For example， the sign of progressive tense -ing and the plural marker /s/ were acquired much earlier than the singular form in third person /s/ and the possessive /s/（Brown， 1973）.
　　3. Differences
　　The differences between the two will be discussed in detailed based on Critical Period Hypothesis， Fundamental Difference Hypothesis and Input Hypothesis.
　　3.1 Age
　　The incidence of native-like competence is very low among adults of SLA， which may be explained by Critical Period Hypothesis （CPH） （Lennenberg， 1967）. Children are better language learners who can achieve easily a success in a second language， while adults cannot usually or very difficult to do that， especially in the term of accent. Normally， children can attain “absolute success” （Slinker， 1972）-- the native-like proficiency and competent， whereas it is not the case for the majority of adults in SLA. Moreover， children have more advantages in acquiring the accent than adults or teenager. Foreign accent may occur among adults even children， if they expose to a second language later （Flege. etal.， 1999）.
　　3.2 Accessibility to UG
　　（1）Full access to UG in Children’s L1 Acquisition.
　　UG serves in L1 acquisition and it has been considered to be “guiding force” in children’s L1 acquisition by many for a long time and “genetic blueprint” which determines the types of grammar （White， 2003）. It constitutes the child’s initial state. Children acquire the first language with finite stimulus and experience， but they can produce and process infinite sentences. It is the innate language faculty that fills in the gap. In most instances， no information concerning perfect utterance， or information only about the imperfect utterance， is available to children （Gass