should

中文： 应该、应当、该、如果

1. Used to issue an instruction (traditionally seen as carrying less force of authority than alternatives such as 'shall' or 'must'). · You should never drink and drive.· The law is clear that you should always wear a seat belt.
2. Used to give advice or opinion that an action is, or would have been, beneficial or desirable. · You should go and see that film. I think you'll enjoy it.· Should we go and see the police, do you think?
3. With verbs such as 'see' or 'hear', usually in the second person, used to point out something remarkable in either a good or bad way. (informal) · You should see his new apartment. It's like a palace!· If you think her piano playing is bad, you should hear her sing!
4. In questions, asks what is correct, proper, desirable, etc. · What do you think? What should I do?
5. Indicates that something is expected to have happened or to be the case now. · They should have finished by now; I'll call them to check.· My fruit trees should be in flower, but the cold spring has set them back.
6. Will be likely to (become or do something); indicates a degree of possibility or probability that the stated thing will happen or be true in the future. · They should have it finished by Friday.· When you press this button, the pilot flame should ignite.
7. Used to form a variant of the present subjunctive, expressing a state or action that is hypothetical, potential, mandated, etc. · If I should be late, I should hope that you are prepared to go on without me.· Should you need extra blankets, you will find them in the closet.
8. Used to express a conditional outcome. (formal, literary) · If I had not been so tired, I should have laughed heartily.

He/she/it should