How to Use- 'Should' and 'Should Have' (Modals) in a Sentence while Speaking English

Use of Should- Should is a modal auxiliary verb.

The basic structure for should is:

subject+auxiliary verb(should)+main verb+object.

We use should mainly to:

1. Duty, Obligation and to give advice

Should is used with pronouns of all the three persons(subjects) to talk about duty and obligation.

Example-

• We should help the needy and the poor.
• Mr.john should meet me tomorrow. 
• I should not lie.
• We should  work for the society.
• You should pay the education fees in time.

2. Indirect speech
Should is the past tense of shall in indirect speech

• The teacher said,‘The student shall be given a reward for good results.’
• The teacher  said that the students  should be given a reward for good results.
• He said ,’he shall help me in difficult situation’.
• He said that he should help me in difficult situation.

3. Possibility/Expectation

Should is often used to express possibility or likelihood.

• My brother should be in New York by now. 
• We  should be able to finish this work in time.
• You should be able to pass in upcoming exams.
• You should be doing this work till today evening.
• They should be able to respond to any query.

4. Conditional statements.

- If I were you I should...
We often use the conditional structure "If I were you I should..." to give advice.

• If I were you, I should complain to the boss.
• If I were you, I shouldn't worry about it.
• I shouldn't say anything if I were you.
• I shouldn't meet him if i were you.

Use of Should have

We use should have + past participle to talk about things we regret / feel sorry(verb/noun) about something that happened or did not happen in the past.

Examples-

• He should have spoken to me before deciding.
• You should have given advice to me on this matter.
• It is very hot outside i should have taken an umbrella.
• I should have called him last night. 

Negative-

• He fought with the guest "I should not have invited him to the party".
• You shouldn't have shouted at servant like that.
• I should not have eaten so much.
• We should not have visited there.

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