Hasn't is the short form of has not. You use it with he, she, it, or a singular name: She hasn't called. The train hasn't arrived. It means exactly the same as has not; the short form just sounds more natural in speech and in friendly writing. In careful or very formal writing, some people still prefer has not, especially when they want to press on the word not. The apostrophe marks the missing o in not. You do not use hasn't with I, you, we, or they — those take haven't. Children meet it very early because we say it all day: hasn't he?, she hasn't finished, it hasn't stopped raining.

has not 的縮寫