"cannot" versus "can not"

我印象很深刻的是我一個句子(I can not recall......)中的can not被劃掉，老師在上頭寫cannot，並註明one word －－ 只有一個字。我從那時候起，就一直沒再寫can not，而是寫兩字併起來的cannot。

好奇怪，"長人"字典沒有說can not的用法是錯誤的，而英文用法大字典也只說cannot是英國用法，can not是美國用法。順帶一提，那位糾正我的老師，是來自UK的。

沒想到，cannot分不分開有沒有差的問題也被列為常問問題之一。(該網站的解釋是說cannot和can not的拼法都可以接受，但cannot是最普遍的拼法，can not是用在像can not only這樣子的情況。)

Languagehat.com:cannot解說的最詳細，他開頭先提到十一版的Merriam-Webster's Collegiate Dictionary把cannot這個字中開放了個空格，變成了can not，他說明了這兩者的不同：

The definition of cannot should be either "the negative form of can" (as the AHD has it) or a periphrasis like "is not able to." The only context in which can not, two words, occurs is as an emphatic alternative: "You can do it, or you can not do it." In that case, it is clearly two separately spoken words, with the not given special emphasis, and equally clearly it means something very different from cannot, namely "have the option of not (doing something)." The only acceptable form for the unabbreviated negative of can (or, if you prefer, for the expansion of can't) is cannot, one word.

給幾個句子來分別看看他所說的意思:
You cannot do it. 你不能做。
You can not do it. 你能不做。

I cannot smoke. 我不能抽煙。
I can not smoke. 我可以不抽煙。(我能不抽煙。)

再讓我們看看網路上面是怎麼說的吧…

下列的說明是取自這裡。


最後這一個是取自這裡。

Tip: Cannot vs. Can Not

"Cannot" is always one word. Even though you can probably think of examples where you want to make it two words, don't. (Ex: You can go to the store, or you can not go to the store.) Try to rewrite it for more clarity instead.