Rule 1: With the verb to be and auxiliary verbs like can, may and will, you add the word not after the verb.
Note! Can + not is written as one word: cannot. Is not, are not and cannot can be shortened to isn't, aren't and can't. The short form of will not is won't.
You aren't at home. / You are not at home.
We can't come now. / We cannot come now.
They won't listen. / They will not listen.