1、can not一般可以缩写为can't。类似could not 可以缩写为couldn't，is not可以缩写为isn't，are not可以缩写为aren't。
而像单独的单词也可以有缩写形式，比如December可以缩写为Dec.
2、例句：I can't tell you the reason.
You can't go there.
I can not remember where my book is.
I can not understand what you are talking.
I can't say you are right.