Modals verbs: Could and should

 

Use of "Could" and "Should".

Could:

Subject + could + infinitive without to.

The modal verb could is a modal verb because it must always be accompanied by another verb with its own meaning and in the infinitive mood (without to). Could is the past or conditional form of can and would be translated as "could" or "knew". It is usually used in the English second conditional. The negative form of this modal verb is couldn't and has the same meaning and uses as could. If you want to know how to form it, read on.

The modal verb could has different functions: 

• Past ability.

    When you want to talk about your abilities in the past; that is, to talk about everything you knew or        could do, use could. 

• Ask for permission in a polite 

    waIf you want to ask permission in a polite or formal way, you also use could. 

Examples: 

 She could ride a horse. 

 She couldn't ride a horse.

Should:

Should is used to express obligations, recommendations or advice, giving an opinion of what is considered right. In English it could be translated as 'should'.

It is used after any personal pronoun and followed by an infinitive verb using the following structure:

Subject + should + infinitive verb.

Uses: 

• To give advice, give opinion or recommend:

        I think you should go to the doctor. 

• To show obligation or duty to say what is the right thing to do:

        I really should be in the office before 9am. - I really should be in the office before 9am.

• To express supposition, deduction, probability or expectation :

        They should be here soon. - They should be here soon.

 

To practice:

Could/couldn't

Should/shouldn't