should 的用法

1） 用作助动词，表示过去将来时态，主语为第一人称。
* I said I should be there before ten. 我说过我十点钟以前到那。
* We said we should finish the work soon. 我们说过我们会很快完成那份工作的。

2） 用作情态动词，表示 “应该”, “应当”
* You should keep your promise. 你应该遵守诺言。
* We should help each other. 我们应该互相帮助。
* You shouldn't come here. 你不应该来这里。
* Should I wear a coat? 我要穿大衣吗？
* There shouldn't be any difficulty about passing the test. 通过考试应该没什么困难。
* You shouldn't have given her so much food. 你本不应该给她那么多食物。
* I shouldn't have shouted at you the other day. 几天前，我本不应该想你大喊大叫的。
* You should be doing your exercises instead of watching TV. 你应该做作业而不是看电视。
* She should have been staying in the library yesterday afternoon. 她昨天中午应该一直呆在图书馆。

3） 用于使语气显得婉转 （只能用于第一人称）
* You are mistaken, I should say. 依我看，你是搞错了。
* I should think it would be better to try it again. 我倒是认为最好试一试。
* We should be grateful for your help. 我们将很感谢你的帮助。

4) 用于表示猜测
* They should be there by now. 他们现在可能到了。
* I think she should be in her office. 我想她应该在她的办公室。
* He should have got a bad cold. 他应该是得了重感冒。
* I should think you were horrified. 我想你们受惊不小吧。

5) 用于虚拟语气中 (详见虚拟语气一章)

6) 用在某些由in case, so that , lest 引导的状语从句中
* He left early in case he should miss the last train. 他早点走，以免错过末班火车。
* Keep quiet in case you should interrupt him.要保持安静，以防打扰他。
* You must wake him early lest he should be late for school．你务必早点叫醒他，以免他上学迟到。