一、时间状语从句
1.when, while, as引导的时间状语从句的主从句动作发生的顺序及主从句的时态要求。
我们在Module 3学习了由when, while,as引导的时间状语从句,本课时主要讲一下它们引导时间状语从句时主从句动作发生的顺序及时态要求。
(1)主从句动作发生的顺序
when与as引导的时间状语从句,主从句谓语动词可以同时发生也可以先后发生;while引导的时间状语从句,主从句谓语动词同时发生或主句动作发生在从句动作进行的过程中。
When he had finished his homework, he took a short rest.
当他完成作业后,他休息了一会儿。(从句动作先发生)
When I got to the airport, the guests had left.
当我赶到飞机场时,客人们已经离开了。(从句动作后发生)
Whilewe were working in the fields, it suddenly began to rain.
当我们在地里劳动时,忽然下起雨来。
(2)主从句的时态要求
如果主句的动作发生于表示"当......时"的时间状语从句中的动作进行的过程中,从句常用进行时。
Someone broke into the house when/while/as she was sleeping.
在她睡觉时有人闯入屋里。
WhenTom was reading, Jim went out to play football.
汤姆看书的时候,吉姆出去踢足球了。
2.表示时间先后的连词主要包括before和after。after表示"在......之后"。before可表达多种意义:"......才";"......就";"还没来得及......就......"等。
before常用于以下句型:
It will be+一段时间+before ...(从句用一般现在时)要过......时间才......
It won't be+一段时间+before ...(从句用一般现在时)过不了......时间就......
It was not long before ...(从句用一般过去时)没过多久就......
It was+时间段+before ...(从句用一般过去时)过了......时间才......
It will be half a year before I come back.
半年之后我才回来。
It won't be long before we meet again.
不久,我们会再见面。
It wasn't long before he left the country.
没过多久他就离开了这个国家。