Can't & cannot

We usually use "can't" in a conversation and "cannot" when we write...

They are just the same. 'can't' is the short form of 'cannot'

eg:

I can't/cannot swim.
I can't/cannot cook without a pot.
I can't/cannot do this in such limited time!

一樣, 祇不過一個簡寫, CAN'T 通常用于對話及無咁 FORMAL時候用

Written English
1) Formal composition
Eg. I cannot walk forever because of this serious accident.
2) Letter
Eg. I can't walk forever because of this serious accident.
Spoken English
1) Eg. I can't walk forever because of this serious accident.
2) Eg. You can sing well, can't you?
Hope this can help you!!!

其實can't 同cannot 係一樣既~
0係用法上亦都係冇分別,
硬係要講有咩唔同,
就只可以話寫書信既時候,
用cannot 會好d, 因為cannot 用起上黎係比can't (short form)有禮貌d~

can't
cannot
其實係一樣~
can't
只係
cannot
的縮寫
就好似:
don't = do not
won't = would not

例:
I can't swim.
I cannot swim
以上兩句意思一樣,
文法都啱!

兩者一樣，用法也一樣
Can't 是Cannot 的簡寫，
正如don't 和 do not一樣