USE OF ‘CAN’ ‘COULD’

I can speak English fluently.
Mark can study eight hours continuously.
George can swim in the sea.
They can perform well today.

My father can visit US this month.
It can rain heavily tonight.
She can come with me tomorrow.
You can win lottery this summer.

Can I help you in this situation?
Can we go there together?
Can I sit here for a while?
Can I use your laptop, please?

You can go now.
They can start to write a paper.
You can‘t park your bike here.
He cannot stay here for a long time.

Richard could be a leader of our team.
You could cause a disease eating like this.
We could go at beach tomorrow.
She could be there with her friend.

I could handle the office skillfully.
My father could speak Latin fluently.
Ahmed could work for ten hours daily.
I couldn’t open the door in that condition.

You could improve your English grammar.
You could support your brother now.
If you agree, we could go there to meet him.
You could buy this product.

Could you help me to complete it?
Could I talk to your mother, please?
Could you reserve one seat for me?
Could you just take you seat and listen?

You could use your tablet to find answers.
Roger couldn’t go to watch movie with friends.
Could I ask something about this poem?
Could I turn the fan on?