语法一:时间状语从句
时间状语从句主要用于说明主句动词的时间,其类型颇多详见如下归纳。
1. When 引导的时间状语从句,意为“当……的时候”,when 的从句可以用延续性动词。 He was working at the table when I went in . 当我进去的时候,她正在桌旁工作。 I was watching TV when he came. 他来的时候我正在看电视。
注意:when 也可以作并列连词,表示一个动作即将或正在进行或刚完成的时候,突然发生了另一件事。
I was about to leave when the telephone rang. 我正要离开,这是电话铃响了。
We were working in the chemistry lab, when the lights went out.
我们正在化学实验室工作,突然灯熄灭了。
I had just gone to sleep when there was a knock at the door. 我刚入睡就有人敲门。
2. While 引导的时间状语从句,表示“与……同时,在……期间”。While 的从句中常用延续性动词或表示状态的词。
They rushed in while we were discussing problems. 当我们正在讨论问题时,他们冲了进来。 Father was cleaning the car while I was playing computer games.
当我正在玩电子游戏时,爸爸在清洗汽车。
注意:while 还可以表示对比意义,意为“而;却”。例如:
Jane was dressed in blue, while Mary was dressed in red.
珍妮穿着蓝色的衣服,而玛丽穿红色的。
3. As 引导的时间状语从句,作“当……的时候,一边……一边”“随着----”解,as 的从句中可使用延续性动词,也可使用非延续性动词。例如:
He sang as he was working.他一边工作一边唱歌。
As time goes by, we have a better understanding of things around us.
随着时间的推移,我们对自己周围的事务有了更好的理解。
4. Before 和 after 引导的从句:前者一边表示主句的动作发生早从句的动作之前;后者表示主句的动作发生在从句的动作之后。例如:
I didn’t know any English before I started school. 我上学之前,一点英语都不懂
I had cooked supper before my parents came back. 我父母回来之前,我就做好了晚饭。 It won’t be long before we meet again. 我们不久就能见面。
After he came out, he locked the door. 他出来后,就锁上了门。
5. Since 和 ever since 引导的从句:表示“自从……以来”,从句一般表示动作的起点,用过去时。主句表示动作延续的情况,一般用现在完成时或现在完成进行时。如果主句表示的是时间,主句可用一边现在时,也可用现在完成时。
现在完成时(延续性动词)…since+…过去时(非延续性动词)“自从……以来”
现在完成时(延续性动词)…since+…过去时 (延续性动词)“自(延续性动词结束以来……” Since he came here , he has made a lot of friends.他来这里以后,已交了许多朋友。
He has been working here ever since he left university.
自从大学毕业以后,他就一直在这里工作。
She has lived alone since her husband died.自丈夫去世后她就一直独自生活。
I have been wearing glasses since I was three.我三岁以后一直戴眼镜。
It is ten years since he smoked.他戒烟十年了。
语法二 过去完成时
1. 过去完成时由助动词had 加过去分词构成,主要表示在过去某时之前已发生的动作或情况,也可以说时“过去时间的过去”。
其被动形式为“had + been + p.p” 例如:
By the end of last term, we had learned more than 3,000 English words.
到上个学期末为止我们已经学了3000 多个单词了。
注意:如果句中出现了表示过去的具体时间状语,句子的内容可为过去的实际情况或句子中的内容为历史事实时,句中的动词时态只能用一般过去时。例如:
The teacher said that it was Columbus who first discovered the American continent.
2. 在表示某人过去未曾完成的“心愿,打算,计划,想法,许诺”等等时,hope , mean ,plan, want ,promise , intend 等位于动词必须用过去完成时。例如:
I had planned to offer you some help in your shop, but suddenly my mother fell ill yesterday. 昨天我原本计划在你的店里帮一些忙的,但是我妈妈突然病了。
He had hoped to spend the important day with us last Sunday , but he was too busy then. 上星期他原本很想与我们一起度过这个重要的日子,可是他当时实在太忙了