do not を短くした形
I don't know him.
I don't know him.
私は彼を知らない.
Do you have a piano?—No, I don't.
会話Do you have a piano?—No, I don't.
君はピアノを持ってるの.—いいえ, 持ってません.
Don't you love her?
Don't you love her?
君は彼女を愛してないのか.
⦣ ×Do not you love ～? としない.
Don't be nasty to your sister.
Don't be nasty to your sister.
妹に意地悪してはだめ.
You know Mr. Green, don't you?
You know Mr. Green, don't you?
君はグリーンさんを知っていますね.
⦣ ～, don't you? は「～ですね」と念を押おす用法. ×～, do not you? としない. 