阅读3

长难句

the word +定语从句(that省略)and the situations +定语从句in which(=situations which... in the situation)

段落大意

1. raise a question: why young children express themself unlike adult?
2. behaviorism made exactly this argument that children learn to talk by copying what they hear ----- proposed 'copycat' theory
3. 'copycat' theory can't explain toddlers' doing what they use one-word in which adults never express themselves
4. proposed 'mental-developmental hypothesis’, means children speak multi-word after their brains are ready
5. proposed 'stages-of-language hypothesis’, means children say sentence of this stage must after they have learned previous stage
6. talk about the deference between those hypothesis
7. study in those hypotheses through adopted kids
8. through the experiment, combining words isn't matters how mature your brain is, but the number of words you know.
9. learning is a gradual process
10. the language learning's 'critical period' have researched long time