[Grammar] difference between can and could

[swami.shreekant2]

hi,
Please can you tell me when to use the can and could word in a framing sentences.
I am totally confusing with these words.
if any one help ..this will make me a proper use in a sentences.

 

[sarat_106]

hi,
Please can you tell me when to use the can and could word in a framing sentences.
I am totally confusing with these words.
if any one help ..this will make me a proper use in a sentences.

Normally both words are used to express ability and possibility or similar such ideas, but there is a difference in their usages.

First, when we refer to past events. Look at the following:
Are you able to read without glasses now a days?
No, I could read without glasses when I was young. (Here you can not use .can’)

See, the second kind of usage:
You can go now. It emphasizes simply that this is an option that's available.
You could go now. It emphasizes that this is a suggestion or piece of advice,

Next while asking a question, we consider "could" more polite than "can."
Ex: "Could you do this?" is more polite than "Can you do this?" ( The "can" question is not incorrect, just less formal/polite)

Finally, in a hypothetical/subjunctive sentence, only one of the two words can be used:
Ex: If today were Sunday, I could rest all day. (this is a hypothetical case because, today is not Sunday)
Ex: If it rains tomorrow, we can stay home.. ( It can be a reality and not unnatural)