You use should when you are saying what would be the right thing to do or the right state for something to be in.
I should exercise more.
我应该多锻炼。
He's never going to be able to forget it. And I don't think he should.
他永远都不会忘记它。而且我认为他也不应该忘记。
Should our children be taught to swim at school?
我们的孩子应该在学校学游泳吗?
You use should to give someone an order to do something, or to report an official order.
18-year-olds are sent reminders that they should register to vote.
给18岁的人派送了通知单,提醒他们应该登记投票。
If you say that something should have happened, you mean that it did not happen, but that you wish it had. If you say that something should not have happened, you mean that it did happen, but that you wish it had not.
I should have gone this morning but I was feeling a bit ill.
今早我本应该去的,可是我有点不舒服。
You should have written to the area manager again.
你本应该再给区域经理写封信的。
You use should when you are saying that something is probably the case or will probably happen in the way you are describing. If you say that something should have happened by a particular time, you mean that it will probably have happened by that time.
You should have no problem with reading this language.
你读这种语言应该不会有问题。
The doctor said it will take six weeks and I should be fine by then.
医生说这将需要6周时间,而我到时应该会康复。
You use should in questions when you are asking someone for advice, permission, or information.
Should I take out a loan?
我该去贷款吗?
What should I do?
我该怎么办?
You say 'I should', usually with the expression 'if I were you', when you are giving someone advice by telling them what you would do if you were in their position.
I should look out if I were you!
如果我是你,我就会小心的。
You use should in conditional clauses when you are talking about things that might happen.
If you should be fired, your health and pension benefits will not be automatically cut off.
如果你失业了,你的医疗和养老金不会自动中断。
You use should in 'that' clauses after certain verbs, nouns, and adjectives when you are talking about a future event or situation.
He raised his glass and indicated that I should do the same.
他举起了他的玻璃杯,暗示我应该照着做。
I insisted that we should have a look at every car.
我坚持认为应该把每辆车都看一看。
You use should in expressions such as I should think and I should imagine to indicate that you think something is true but you are not sure.
I should think it's going to rain soon.
我觉得很快就会下雨了。
You use should in expressions such as You should have seen us and You should have heard him to emphasize how funny, shocking, or impressive something that you experienced was.
You should have heard him last night!
你真该听到他昨晚说的话!