have是用于第一人称复数 has用于第三人称单数 do与does一样的道理 比如说 I（we they) have a book. He(she) has abook. I love you.这是第一人称作主语 He loves me.第三人称作主语
does、has是用在三单式后面如：在用does和has时，通常主语是she,he,it,my mother、my wife(类似的一些单数物体）、everyone....而时态一定要是一般现在时。
1.She has a cat. She does her homework. 2.My mother have a sister. My mother does housework. 而do，have是用在主语是I、They、our、my friends,my parents,my pets(一些复数物体）的句子中，时态也一定要是一般现在时1.I have a dog .They do them homework .
