How to use can and could?

You can dramatically improve your English proficiency by learning to leverage the expansive potential of key verbs. These versatile words allow you to convey a wide range of situations in both written and spoken language.

Can is one word among them. Could is the past form of it. 

*You can use them to shorten your sentence.

Can is a modal verb. And you must use it to improve your English. Interestingly I have already used this modal verb at the beginning of this article.

ok, let's see where you can use the "can".

ABILITY, POWER, CAPACITY

You can use the ‘can’ to express ability, power, and capacity. Let me give you examples.

Ex- Rishi is able to finish the task in two hours.

The same sentence can be written using the modal (can).

“Rishi can finish the task within two hours.”

Such as I have no power to move a truck.

I cannot move a truck.

Mahesh is very weak. He has no capacity to lift 10kg.

Mahesg is very weak. He cannot lift 10kg.

POSSIBILITY

In a word to express possibility you can use can.

Ex- It is possible for me to go there.

By using can the sentence  will be like “I can go there.”

It is not possible for me to meet him right now.

Using can “I cannot meet him right now.”

RIGHT

You have no right to enter my house without my permission.

Using can “You cannot enter into my house without my permission.”

Teachers have the right to punish the students.

“Teachers can punish the students.”

OFFER OF HELP

In this usage using can makes the sentence interrogative. Such as ‘I offer help to solve this problem for you.’

“Can I solve this problem for you?”

Likewise

I offer help to find you something.

 "Can I help you find something?"

 I offer to carry that bag for you.

 "Can I carry that bag for you?"

 "Can I help you set that up?"

 "Can I take a look at that for you?

The reason for becoming interrogative is if you want to use it in an assertive sentence it may sound like you will do the work for him without his consent.

POLITE REQUEST, APPEAL

While requesting someone ‘can’ is used.

Ex- Rishav requests the use of his computer.

Using can: Can Rishav use his computer?

Can I ask you a quick question?

"Can I trouble you for a glass of water?"

  

TO SEEK PERMISSION AND TAKE PERMISSION

I need your permission to go to Rishav’s house, father.

Can I go to Rishav’s house, father?

You are not permitted to watch the movie.

You cannot watch the movie.

IMPOSSIBILITY, DOUBT, DISBELIEF

It is impossible for him to be the person.

Can he be the person?

He is my friend. I doubt he tells me a lie.

Can he tell me the lie?

"Can you believe that? Our friend has made a world record.

CONFIRMATION, CERTAINTY

Surely, Bivash is not coming.

Bivash cannot come.

Now the rules of using could:

POLITE REQUEST

I request you to fill up the form for me.

Could you fill up the form for me?

I request you to let me book tickets for us.

Could I book the tickets for us?

WISH or DESIRE

I desire to fly in the sky.

I wish I could fly in the sky.

SURPRISE, ASTONISHED

It is a surprise that you have done this to me.

How could you do this to me?

A GENTLE DOUBT

This person was there when I left the office. He might left the door open.

He could be the person who left the door open.

Hey, do you have any question about can or could? Feel free to ask in the comment section.