can✀t 和cannot有什么不同

can't 是cannot的缩写形式，但正式场合下，cannot比can't的语气更强烈，正式英语书面是不能用can't 其他缩写也不行的（这里指的是类似英语议论文这样的..），，口语一般用can't而不用cannot

To say that you are not able to do something, you say "you cannot" or "you can't (more colloquial口语). 但"can not" is NOT 书面语! It is only a grammatical error. It should always be spelled together and like "cannot". Please read New York Times or other journals or newspapers to see if "can not" actually exists.
注意一下啊 cannot 千万不要写成了 can not 啊，意思不一样啊
Cannot是“不可以”，而can not是“可以不”。

举个例子：
I cannot believe this! （我无法相信！等于I can\'t believe this!）

I can not believe this! （我可以不相信！也就是说，I can believe this, or I can not believe this。我并不一定要相信，我可以选择不相信。）