含有实义动词句，Do和Does来出力；单三主语用Does，其余人称都用Do；一般疑问很好变，Do和Does提句前；句首是Do是Does，后面动词都还原；否定句也不难，主语后don’t，doesn’t跟上前；不论疑问否定句，人称或是一二三，实义动词必还原，does、has永不见。
1.肯定句
(1)I have a blue book.
(2)He has a brother.
(3)She wants to be a teacher.
(4)They like to play basketball.
2.否定句：主语+don’t/doesn’t+动词原形。其中do/does为助动词，是来帮助实义动词构成否定或疑问句的，但加了do/does后，其后面的动词必须用动词原形。
(1)I have a blue book.(变为否定句)→I don’t have a blue book.
(2)He has a brother.(变为否定句)→He doesn’t have brother.
(3)She wants to be a teacher.(变为否定句)→She doesn’t want to be a teacher.
(4)They like to play basketball.(变为否定句)→They don’t like to play basketball.
3.一般疑问句：Do/Does +主语+动词原形+其他？句中加了do/does后，其后面的动词还是必须用动词原形。
(1)I have a blue book.(变为一般疑问句)→Do you have a blue book?
(2)He has a brother.(变为一般疑问句)→Does he have a brother?
(3)My brother does his homework before supper.(变为一般疑问句)→Does your brother do his homework before supper?
(4)She wants to be a teacher.(变为一般疑问句)→Does she want to be a teacher?
(5)They like to play basketball.(变为一般疑问句)→Do they like to play basketball?
4.特殊疑问句：特殊疑问词+一般疑问句?
(1)Your sister likes English best because it’s interesting.(对加粗部分提问)→Why does your sister like English best?
(2)He does his homework before supper.(对加粗部分提问)→When does he do his homework?
注意：当含有and引导的短语在句中做谓语或宾语，我们把这类句子变否定句时，必须把and变为or.如：
(1)He can swim and dance.(变为否定句)→He can’t swim or dance.
(2)My father likes English and math.(变为否定句)→My father doesn’t like English or math.
5.but和except后。but前是实义动词do时，后面出现的不定式不带to。
例如：He wants to do nothing but go out.他只想出去玩。
比较：He wants to believe anything but to take the medicine.除了吃这药，他什么都信。
