题目内容：
For Questions 6-10．you will hear a lecture about child development．While you listen，com-plete the sentences and answer the question．Use no more than 3 words for each answer．You will hear the recording twice．You now have 25 seconds to read the sentences and the questions below．
| Who is the speaker talking to? | 6． |
| What is the main topic of this talk? | 7. |
| When do children first begin to make language like noises? | 8． |
| At what age do most children begin to master the basics of grammar? | 9. |
| What does the speaker say about the grammatical mistakes that four-year-olds make? | 10． |
参考答案：
答案解析：