Input hypothesis: 语言输入说a hypothesis proposed by Krashen, which states that in second or foreign language learning, fro language Acquisition to occur, it is necessary for the learner to understand Input language which contains linguistic items that are slightly beyond the learners’ present linguistic Competence. Learners understand such language using cues in the situation. Eventually the ability to produce language is said to emerge naturally, and need not be taught directly. 指Krashen指出的一个假说，认为在第二语言或外语学习中，要使语言习得得以发生，有必要让学习者理解的输入语言包含稍高于其现有语言能力的语言项目。学习者利用情境提示理解这些语言，最后，据说很自然地出现产生语言的能力，而无须直接传授。

1.1  Individual differences个体差异

(in the process of learning a foreign language, some students could learn it very well and efficiently, and others otherwise在学习外语过程汇总一些学生可以学习非常好，并且很有效率，另一些则相反。

To let the students guess the reasons: attitude, IQ, time,)

1.      Language aptitude语言能力 a natural ability for learning a second language学习第二外语的天生能力    IQ

2.      Motivation:动机the learner’s attitudes and affective state or learning drive学习者的态度、情感状态、或学习动力

1）Instrumental motivation工具性东西 （考试，得升迁，职称考试）

2）Integrative motivation综合性动机 （为了了解另一个种文化）

3）Resultative motivation结果性动机 （为了外部目的，打赌）

4）Intrinsic motivation内在动机 （享受快乐）

主要是Instrumental motivation工具性东西 和Integrative motivation综合性动机

3.      Learning strategies学习策略 learners’ conscious, goal-oriented and problem-solving based efforts to achieve learning efficiency.学习者有意识的，以目的为导向和以解决问题为基础为提高学习效率而作出的努力。

1)      Cognitive strategies认知策略analyzing, synthesis, internalizing分析，综合，内在化

2)      Metacognitive strategies元认知策略planning, monitoring, evaluating计划，监控，评价

3)      Affect/social strategies影响/社会策略interacting or communicating交流和交际

4.      Age of acquisition习得年龄

   Critical Period Hypothesis:临界假说 the theory that in child development there is a period during which language can be acquired more easily than at any other time. According to the biologist Lenneberg, the critical period lasts until puberty (around age 12 or 13 years), and is due to biological development. Lenneberg suggested that language learning may be more difficult after puberty because the brain lacks the ability for adaptation. This, he believed, was because the language functions of the brain have already been established in a particular part of the brain; that is, because lateralization 偏侧优势(see Brain) has already occurred by this time.认为儿童发展时期内有一段时间语言习得最顺利的一种理论。根据生物学家Lenneberg，关键时期持续至青春期（约十二或十三），这是处于生物发展原因。他还提出，语言过了青春期，由于大脑缺乏适应能力，会变得越来越难。他认为，这是因为大脑的语言功能已经在大脑某一部位确立，也就是因为这个时期偏侧优势已经出现了。

5. Personality个性 extroversion, talkative, self-esteem, self-confidence----successful