notの短縮形は前の語と結びついて「－n't」となるものが多いです。

 

[いろいろな語と結びついたnotの短縮形]

is not → isn't

are not → aren't

do not → don't

does not → doesn't

can not → can't

 

He is not a doctor. → He isn't a doctor.（彼は医者ではありません）

They do not play baseball. → They don't play baseball. （彼らは野球をしません）