be动词，情态动词，助动词do/does的用法区别及练习助动词，顾名思义就是帮助动词完成疑问及否定的，本身没有什么含义。
主要的助动词有be,do,will,have 等，其用法详述如下：—、(D由连系动词am, is, are构成的句子：变一般疑问句时把am, is, are提到句子的前面，句尾用问号即可。
变否定句时直接在am, is, are后面加not即可。
例如：肯定句:He is a student.—般疑问句:Is he a student?否定句:He is not a student.画线提问:对he提问:Who is a student?对 a student 提问:What is he?(2) was是am,is的过去式，were是are的过去式，若句子中有以上两词时，变疑问句及否定句方法与(1)相同。
二、(1)由情态动词can, may,will , shall等构成的句子：变一般疑问句时把can, may,will ,shall提到句子的前面,句尾用问号即可.变否定句时直接在can,may后面加not即可.例如:肯定句:She can swim.—般疑问句：Can she swim?否定句:She can not swim.画线提问:对she提问:Who can swim?对swim 提问:What can she do?(2) could,might,would,should是can,may,will,shall的过去式，若句子中有以上两词时，变疑问句及否定句方法与(1)相同。
三、(1)由行为动词构成的句子：需要加助词do或does.变一般疑问句时把do/does放在句子前面•变否定句时把do” t/doesn放在动词的前面。
要注意观察动词的形式并对号入座。
一般疑问句和否定句的动词三单式都要变回原型。
play ---- do plays -------- oes例如：肯定句:They play football after school. He plays football after school.—般疑问句：Do they play football after school? Does he play football after school?否定句:They don't (do not) play football after school. He doesn ' t' play football after school. 画线提问:对they/he 提问:Who plays football after school?对play football 提问:What do they do after school? What does he do after school? 对after school 提问：When do they play football? When does he play football?(2) did是do和did的过去式，变一般疑问句时把did放在句子前面•变否定句时把didn ' t放在动词的前面，要注意观察动词的形式并对号入座。
一般疑问句和否定句的动词都要变回原型。
四、(1)由have,has构成的现在完成时句子，变一般疑问句时把have,has提到句子的前面，肯定句: He has read today1 s n ewspaper.—般疑问句 : Has he read today1 s newspaper.?否定句:He has not read today1 s newspape画线提问:对he 提问:Who has read today1 s newspaper?对today1 s newspaper 提问:What has he did?（2） had是have和has的过去式，在构成的过去完成时句子中，变一般疑问句时把had提到到句子的前面，句尾用问号即可。
变否定句时直接在had后面加not即可。
⑶若have,has,had没有出现在完成时的句子中，则当实义动词对待，请参考实义动词的用法。
五、第一人称I, we在变疑问句时，应变为第二人称you。
"I am, you /we /they are n这是初一最简单的固定搭配，不应再唠叨了吧！六、is,has,does用于第三人称的现在时态，was用于第三人称的过去时态。
针对性练习按要求改写句子：1.1have been to Beijin （—般疑问句）___________________________ t o Beiji n?2.We can see some birds.（—般疑问句丿_____________ see __________ b irds?3.He desig ns clothes.（—般疑问句）_____ he ____________ c lothes?4.There were some flowers on the teachers —般疑问句）________________________ flowers on the teachers 1 desk?5.There were some apples on the tree.（否定句）There __________________________ a pples on the tree.6.1think he is very old.（否定句）I _______ thi nk he ______ very old.7.Please colour it green.（否定句）colour it gree n.8.They had lunch （变否定句丿9.You may have some hot dogs.（—般疑问句）？•10.There aren r t any pears in the 同义句）There are ________ pears in the box.11 • This sign means “ No smoking「What _________ this sig n _________ ?12.She has already written the letter.（改为否定句）she ____________________________________________13.She was you ng.（改为一般疑问句）?■14.My pencils are in the pencil-box.（对划线部分提问）________________ your pen cils?15.1got up at six yesterday （对划线部分提问）_____________________________ you get up yesterday?16.They liked to walk home.（改为一般疑问句）______ they ___________________________________________ ?17.These are cars.（用buses改写成选择疑问句）Are these cars ______________ ?18.My plant is one month old.（就划线部分提问）__________________________________ pla nt?19.Two boys are in our house.（改为there be 句型）______________ two boys in our house.20.My plant has two green leaves.（就划线部分提问）____________________________________________________ pla nt _____________ ? 21.Miss Li goes to Hong Kong by pla ne.（同义句）Miss Li _____________________ Hong Kong.22.The wome n worked in the shoe factory.（就划线部分提问）__________________________ wome n _____________ ?23.He is happy, because he is going to take a trip tomorrow.（就划线部分提问）?■24.My father can cook the meals （就划线部分提问）_____________________________ father ______________ ?25.You should add water often.（一般疑问句）__________________________ water ofte n?、变否定句时相关词的改变肯定句变否定句时，除将谓语变为否定式外，句中其他词语也可能随之改变，如将some 改为any, too 禾口also 改为either, already 改为yet, and 改为or 等：There are some birds in the tree.树上有些鸟。
TThere aren ' t any birds in the tree 树上没有鸟。
He likes the girl, too.他也喜欢这个女孩。
THe doesn' t like the girl, either.他也不喜欢这个女孩。
We have already seen the film.我们已看过这部电影。
TWe have not seen the film yet.我们没有看这部电影。
He likes singing and dancing.他喜欢唱歌和跳舞。
T He does n* t like sin gi ng or dancing他不喜欢唱歌也不喜欢跳舞。
二、部分否定与完全否定比较以下句子：All of us laughed when we heard it.听到这事时我们都笑了。
（肯定句）All of us didn ' t laughed when we heard听到这事时我们并未都笑。
（部分否定）Not all of us laughed when we heard it.听到这事时我们并未都笑。
（部分否定）None of us laughed when we heard it.听到这事时我们都没笑。