English Grammar for proficiency: Modal verb 'should'.

Should is the past tense of ‘shall’. It is generally used to say that something is the proper or best thing to do. It also has many other usages.

Usage

Ideal
It is used to indicate something that is thought to be the right, good, or ideal thing to do.

• We should be respectful to our elders.

• People should be honest in their relationships.

• There should be more parking spaces in this area.

• I should call my parents to let them know I'll be late.

Advice
It is used to give a recommendation or make suggestions.

• You should study for the exam.

• He should wear a jacket; it's quite cold outside.

• You shouldn't be rude to others.

• I think you should apologize for what you said.

Expectation
It is used to indicate something that is expected or likely to happen.

• He should be at work now.

• It should be sunny tomorrow.

• The package should arrive by Friday.

• After studying all night, you should perform well on the exam.

• The bus should arrive at the station in about 10 minutes.

Indirect speech
It is used in indirect speech in the past tense structure.

• He said he should arrive by noon.

• He suggested that I should apply for the job.

• She expected that the package should be delivered yesterday.

Should have
It is used to express something that we wanted to happen in the past but it did not happen.

• I should have studied for the exam last night.

• They should have finished their project by now.

• You shouldn't have spoken to her like that.

• We shouldn't have gone to that party; it was boring.

Clause
It is used in conditional sentences to express an assumed outcome.

• If it rains, we should stay indoors.

• Should you change your mind, let me know.

• In case you should have any questions, don't hesitate to ask.