英语时态的一致
1.在由下面的词短语引导的条件状语从句、时间状语从句、让步状语从句，主句如果是将来时态或有情态动词，从句一般用现在时态表示将来。这类词或短语有：
if, unless, as, when, as soon as, each time, until, even if, after, before, while, whenever, till, whatever, the moment, every time, so long as, no matter how (what, when…) on condition that,
2.主句是现在或将来范畴的时态，宾语从句的谓语动词可以是任意时态，不受主句谓语动词的影响。如
Jim believes that he will get the job.
吉姆相信他会得到这份工作的。
The officer has just told us （that） his annual leave was approved.
这个官员刚告诉我们，他的年假被批准了。
2. 主句的谓语动词是过去时态，从句的时态通常是过去范畴的时态，
1）当从句的动作与主句的动作同时发生，从句中一般用一般过去时或过去进行时。如：
Tom he was busy yesterday.汤姆说他昨天很忙。
Lily failed because she did not submit the project report.
丽丽失败了，因为她没有递交工程报告。
2）从句的动作发生在主句之后，从句时态用过去将来时。
3）从句的动作发生在主句之前，从句时态用过去完成时。
4）从句的动作紧接着主句动作之后发生，尤其在after, when, as soon as,或有immediately, the moment, the minute引导的从句中，通常用一般过去时。
Although David was unwell, he went to office as usual.
虽然大卫身体不好，但他还是去了办公室。
Janet wanted to know why she was not given a more important job.
珍尼特想知道为什么不给她一些重要的工作。
在下面几种情况下， 从句时态用一般现在时。
当宾语从句表示客观真理。
当宾语从句表示的是科学原理时。
当宾语从句表示的是自然现象时。
当宾语从句表示的是某一阶段存在的客观事实时。
当宾语从句表示现在经常性或习惯性的动作时。
当宾语从句表示谚语或格言时。
Newton discovered that gravitation causeds apples to fall.
Our elders told us that experiencce is the best teacher.
3. 定语从句中的时态最自由，最不受拘束。
Tom mooted the idea which some ignored, which others tend to attack, but which many will eventually accept.
汤姆提出这个曾被有些人忽略，有些人试图攻击，但最终会被大多数人接受的想法。
4. Since引导的从句在主句之后，应是时间状语从句，用一般过去时，主句则是现在完成时；since引导的从句在主句之前，一般是原因状语从句，主句是将来时态或有情态动词，从句应是现在时态。
Since he has come, you needn’t go.
既然他来了，你就不必去了。
It has been over a year since Icamebackfrom the countryside.
我从乡下回来已经一年多了。
5. Nosooner...than,hardly...when, scarcely...when中，no sooner, hardly, scarcely 引导的句子通常用过去完成时，而than，when引导的句子则用一般过去时。如
No sooner had we sat down than we found it was time to go.我们刚刚坐下就发现该走了。
The game had hardly begun when it started raining.
比赛刚刚开始就下起雨了。
Scarcely had we arrived when he had to leave again.
他刚到就不得不又要离开。
7.if引导的非真实条件句，wish后的宾语从句，应用虚拟语气。如：
I wish that I had never met you!
我要是从未遇上你多好！
I wish I were a bird. 我要是只鸟就好了。
The party was awful, and we all wished we had never gont to it.
那次聚会真糟，我们真希望自己没有去。
8.主句中如果含有表示请求、命令、建议等意义的词，后面的宾语从句、主语从句、表语从句中的谓语动词用should加动词原形或省去should。如：
My father suggested that we (should) do the job at once.
我父亲建议我们立刻做这项工作。
The suggestion that the sports meeting (should) be put off was rejected.
推迟运动会的建议被否决了。
It is quite natural that such fears (should) arise.
产生这样的疑虑是很自然旳。
9 It is time (high time) 和would rather 后的从句的时态一般用过去时。如：
It was time we went home.我们该回家了。
It is high time we stared (should start).
我们早该动身了。
I’d rather you didn’t tell him.
我倒宁愿你没告诉他。
10.It is the first time 后的从句应用现在完成时态。如：
It was the first time I had ever been in a plane .
那是我第一次坐飞机。
习题
1-Hurry up!Alice andSue are waiting for you at the school gate.
- Oh!I thought they ____ without me!
A went B. are going
A. have gone D. had gone
2.I decided to go to the library as soon as I ____
A finish what I did
B. finished what I did
C.would finish what I was doing
D.finished what I was doing
3.He knew that he _____ to perform in the New Year’s Concert.
A. will be invited B. had invited
C. wouldbe invited D.invited
4.The woman bought a blouse last week. When she washed it, the colors _____.
A. ran B. lost C. fell D. went
5. The football match ____ on for half an hour when he turned on TV.
A. has been B. had been
C. will be D. would be
答案 1 D 2. D 3.C 4.B 5.B