作者：邱世才
这一单元学过的每句话几乎都离不开should和could, 你们肯定对它们两个产生了很大的兴趣吧。那么你们首先要清楚一点，should和could属于两个情态动词。
情态动词，简单地说，它表示的是说话人对动作的观点，既需要、可能、意愿或怀疑等。
一、情态动词should
1. should可以用于第一人称或第三人称的疑问句中，表示征求意见。
例如：1) My brother likes to listen to CDs. He often plays his CDs too loud. What should I do?
2) Dennis wants to take part in the summer camp. But he doesnt have enough money. What should he do?
2. should 表示义务，可以用于提供建议，表示“应该”, 后面跟动词原形。
例如：-Maria argued with her mother last night. She is very upset now. What should she do?
-I think she should say sorry to her mother.
3. should也用于表示某事发生的可能性，用于表示推测的词，意为“可能”。
例如：They should arrive soon.
二、情态动词could
本单元所学习的could不仅仅是充当can的过去式，而是一个单独的情态动词，表示“能；可以”，用来提供建议，后面跟动词原形，它和should在意义上不同，前者是“可以”，后者是“应该”，表示不同的态度，但两个都可以用来提供建议。
例如：-I will take part in a party tomorrow night. But my clothes are out of style. I need some money to buy some clothes in style. What should I do?
-You could borrow some money from your friends.
-No, I dont like to do that.
-Then you should get a part-time job and make some money.