The difference between can and could when we ask questions in the present tense. Can( a model verb, ability, possibility, obligations) asking for a permission also making a request. Ex: can I borrow your pan? Ex :Can I ask you favor? Ex: Can you call back later? Ex: Can you grab me that book? Ex: Can u please stop making such a racket? Bonus word: reproach( to criticize to tell people u did something u shouldn't do in a very polite way ) Could 1. the past tense of can; the same meaning as can, but more polite and formal Ex: Could I borrow your pan? Could I ask you a favor? How could we help? (Both are mpre polite) 2. possibility for past and future. Ex: We could've gone out, but we decided to stay at home. Ex: U could win the lottery, if u buy a ticket. 3. past tense of "can"(u were able to) Ex: When I was younger, I could lift the weights without being soar next day.(talking about ability in the past) Ex: When we first met, we could talk for hours on the phone. Ex: When I was a kid, I could run around all day and never get tired.

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AEE 2296: Can You Understand This English Grammar? 1. can , indicates ability, possibility, suggestion, obligation义务 职责 asking for permission 请求许可/允许 eg, can i borrow your pen ? can i ask you a favor ? making requests 请求 要求 eg, can you call back later ? can you grab me that book ? making offers eg, can i help you anything ? can we do anything for you ? reproaching / critisize sb 责备 申诉 批评 eg, can you please stop making that noise? why can't you just be nice to her instead of upsetting her ? 2. could, not just for the pass tense, the same meaning as can, but sounds more polite, formal and indirect . eg, could i please have the stakes (in restaurants order food) could you pass me the bread please ? could i get anything else ? to indicated possibility in present and future. eg, we could have gone out but we decided to stay home . you could won the lottery博彩if you buy a ticket. use could in pass tense. the ability we have in the pass. eg, when i was younger, i could lift weights without being sore 疼痛 酸痛 the next day. = when i was younger, i was able to lift weights without being sore the next day. when we first met, we could talk for hours on the phone. when i was a kid, i could run around all day and never get tired. (i can do this in the pass) same, i can't do that now.(i couldn't do that now) did you hand out with friends a lot in your neighborhoods ? oh yep we go in the neighbors and say can Molly come out and play ? same we all play at the backyard until my mom would came out and say can you please stop making such a racket吵闹 ? and in the backyard it could be a desaster we have to clean it up. my friends are pretty good at about asking help they could help though.