Section Ⅳ　 Grammar & Writing

　　时间状语从句&过去完成时

　　观察下列从Reading and Vocabulary中选取的句子，体会时间状语从句以及过去完成时的用法。

　　1．He learned to play the harpsichord when he was four, he started composing music when he was five, and when he was six, he played the harpsichord in a concert for the Empress of Austria.

　　2．While he was still a teenager, Mozart was already a big star and toured Europe giving concerts.

　　3．Did he stop composing when he became deaf?

　　4．He showed musical talent when he was very young, and learned to play the violin and piano from his father, who was a singer.

　　5．After they had known each other for many years, Beethoven said, "He is a good composer, but he has taught me nothing."

　　6．As he grew older, he began to go deaf.

　　7．Other composers had written symphonies before Haydn, but he changed the symphony into a long piece for a large orchestra.

　　8. By the time he was 14, Mozart had composed many pieces for the harpsichord, piano and violin, as well as for orchestras.

　　一、时间状语从句

　　时间状语从句用来说明主句谓语动词发生的时间，由连词引导，本模块主要学习when, while, as引导的时间状语从句。

1．when引导时间状语从句时可以和延续性动词连用，也可以和短暂性动词连用，主句和从句中的动作或事情可以同时发生，也可以先后发生。