Section Ⅳ　 Grammar & Writing

　　时间状语从句&原因状语从句

　　观察下列从Vocabulary and Reading和Reading and Listening中选取的句子，体会时间状语从句以及原因状语从句的用法。

　　1．When he was orbiting in the capsule, he took photographs of planet earth.

　　2．When Yang landed, Premier Wen Jiabao telephoned the Control Centre to offer his congratulations.

　　3．While he was travelling in space, Yang spoke to two astronauts aboard the International Space Station.

　　4．Since no one else saw the aliens, not many people believe Mr Bates.

　　5．Now that I have made this first visit, I hope I can come many more times.

　　6．"As you have asked me so nicely，" said Sharon, "I'd be delighted to sign your arm."

　　一、时间状语从句

　　除了我们在Module 3学习的由when，while, as引导的时间状语从句外，常见的引导时间状语从句的连词还有：

　　1．before引导时间状语从句时，有"在......之前"；"......才......"；"......就......"；"还没来得及......就......"等多种意义。

　　He had left before I could say something.

　　我还没来得及说点什么，他就离开了。

　　It was two weeks before everything returned to normal.

　　两星期后一切才恢复正常。

　　It won't be long before we meet again.

　　不久我们就会再见面。

2. since引导时间状语从句时，表示"自从......以来多久了"，从句中的