每年，在世界的某些地方都会发生飞行事故。

Listen Read Learn

Every year, some place in the world, an accident involving an airplane occurs. These accidents are painful because of great numbers of passengers that they carry. Although these are few in number, a great, many people die when even one airplane crashes. Even with the problem of terrorism, the chance rate is low for airplane crashes. Statistics show that you are many more times likely to be killed in a car accident than in a plane crash. Thousands of planes fly around the world each minute of every day. Despite this, we rarely hear of air accidents. People use their emotions instead of logic in dealing with the problems of air travel. With the coming of modern emergency measures and air safety, airplane accidents are actually beginning to decline in number. The reasons for airplane accidents are usually because of pilot error. Other problems can come when the plane hits a rocky air stream or rough weather. Regular overhauls of the planes can help to deter many of these mechanical problems. Pilots can also be rotated more to decrease fatigue or other personal hazards. If precautions are taken, many airline incidents could have been avoided.

听看学

每年，在世界的某些地方都会发生飞行事故。由于飞机承载大量的乘客，所以这些事故让人痛心。尽管飞行事故数量很少，但即便一架飞机坠毁，就会有很多人丧生。事实上，即便有恐怖主义的问题存在，坠机的几率还是很低的。统计数据表明，相对于坠机而言，一个人更有可能死于车祸。每天，每分钟，全世界有数千架飞机在飞行。尽管这样，我们还是很少听说空难。人们在对待飞行问题时，往往凭借情感而非逻辑。随着现代紧急措施和空中安全的应用，飞行事故的数量实际上开始不断减少。飞行事故通常是由飞行员的错误而引起的。其他问题可能是技术上或电力系统的原因，比如导航系统。当飞机遇到波动气流或坏天气时也可能出现问题。定期检查飞机有助于阻止许多技术问题的产生。可以增加飞行员轮流值班的次数以减少疲劳和其他个人危险行为的发生。如果采取了预防措施，许多飞行事故都可以避免。

语法小结 Grammar
时间状语从句

时间状语从句是比较常见的一种状语从句，它可以由when, while, as, before, after, till, until等引导。

1.由when, while, as 引导

When you think you know nothing, then you begin to know something.

当你以为自己一无所知的时候，你就开始知道一些事情了。

Strike while the iron is hot.

趁热打铁。

Our teacher laughed as she spoke.

老师边说边笑。

注意：when, while 和 as 的区别在于：when 引导的从句的谓语动词可以是延续性动词，也可以是瞬时动词，when 有时表示“就在那时”；while 引导的从句的谓语动词必须是延续性的，强调主句和从句的动作同时发生，while 有时还可以表示对比；as 表示“一边……一边……”，引导延续性的动作，一般用于表示主句和从句动作同时发生。

2.由before和after引导

My father had left for America just before the letter arrived.

我爸爸在到信之前去美国了。

Please let me know after you decide.

你决定后请让我知道。

3.由till或until引导

I didn't go to bed until/till I finished my homework.

我作业做完了才睡觉。

It was not until the class was over that he began to teach me English.

直到下课之后他才开始教我英语。

家庭总动员 Do it together

两人一组，一方朗诵下面的中文句子，另一方说出相对应的英语句子。

1.他走了以后我才知道这件事情。

2.你做完作业以后告诉我。

3.你锁门的时候注意到了吗？

4.饭前要洗手。

5.我下车时看到他了。

1.I saw him as I getting off the bus.

2.I didn't know that until he left.

3.Please wash your hands before eating.

4.Tell me after you finish your homework.

5.Do you notice that when you lock the door?