長沙奧數網編輯整理了在小升初中情態動詞的用法並對此進行了對比分析，供大家參考！情態動詞只有情態意義，即它所表示的是說話人對動作的觀點，如需要、可能、意願或懷疑等。
情態動詞的特徵：
1.在形式上，情態動詞沒有實義動詞的各種變化。
2.在意義上，大多數情態動詞有多個意義。
3.在用法上，情態動詞與助動詞一樣，須後接動詞原形。
情態動詞各自的基本意義及用法
一、can 與could用法對比表
對比點 can could
1、表「能力」 Can you lift this heavy box? I couldn’t understand what he said at all.
2、表「許可」 You can use a different material instead. He said I could borrow his bike.
3、「懷疑」 No, no, it can’t be true.
What on earth can this mean? We thought the story could not be true. How could you be so careless?
4、can與be able to 區別 1. could代替 can，表示語氣更為婉轉。
Eg. Could I use your bike? Yes, you can.
2. can (能夠)=be able to(僅表能力時)，但be able to 表示一番努力後，才能做得到，且有更多的時態。
He was a good swimmer, so he __________ swim to the river bank when the boat sank.
A. could B. might C. shall D. was able to
二、may與 might用法對比表
對比點 may Might
1．表「詢問」 May I …?(=Can I …?) Might I …?(=Could I…?)(但比用may 更客氣)
2.表「允許」 You may take the boy there. He told me he might come .(might 與told相呼應)
3．表「可能」「或許」 She may nor like this place. I’m afraid he might not like this play.
註： 1. May I…?的答語。
2.may可表示期望或祝願
May you succeed !
3.may (might)用於目的狀語從句中 肯定：Yes, you may.
否定：No, you mustn’t 不行（語氣強硬）
No, you may not 或No, you』d better not.
The emperor gave them some gold in order that they might begin their work at once.
三、must與have to的用法對比表
對比點 must have to
1．表「必須」 （主觀看法）必須；沒有過去式，可用於間接引語中。He told me I must do according to what he said. （客觀需要）不得不，有多種時態。It’s raining heavily, we can’t go now.
2.疑問句 Must I …?
Yes, you must.（一定）
No, you needn’t./ you don’t have to.(不必) Do you have to go today?
Yes, we do.
否定句：You don’t have to worry about that.
四、need與dare的用法對比表
對比點 need dare
1.情態動詞+動詞原形
1）否定式
2）疑問式 He need not (needn’t)go.
----Need we do it again?
---No, you needn’t do it again. He dare not say so.
Dare she go out alone at night?
How dare you say I’m unfair?
If he dare do that, he』ll be punished.(條件句)
I dare say.(固定用法)
2.行為動詞+帶to不定式
1）肯定式
2）否定式
3）疑問式 He needs to go.
He doesn’t (does not)need to go.
Does he need to do it again?
No, he doesn’t need ot do it again. He dares to say.
He does not(doesn’t)dare to say.
If you dare to jump into the water from here, so dare I .
3. did not need to do
表示過去沒有必要做 She didn’t need to attend the meeting yesterday, and she stayed with her children.(她沒有參加)
五、should與ought to用法對比表
對比點 should ought to
1、表「應該」 表勸告、建議
You should listen to the doctor’s advice.
We should learn from Zhang Hua 表示「有責任有必要」做某事
You ought to finish your work before you go home.
We ought to help each other.
2、表「估計」
They should get home by now. 表示「非常可能」的事，可譯為「總應該」
If we start to work right now, we ought to finish it before lunch.(午飯前應當能幹完)
註： 1）、should還可在虛擬語氣中的使用
2). 注意：ought to的疑問式及否定式
----Ought he to go? ----Yes, I think he ought to.
No, he oughtn’t to.
否定式：ought not to a或oughtn’t to do(不說ought to not do)
反疑問句：oughtn’t ______?
六、shall與will的用法對比表
shall Will
1. 徵詢對方意見或請求指示，用於第一、三人稱：
Shall I (we)…?
Shall he (she)…?
Where shall I (we)wait for you? 1． 詢問對方的意思或向對方提出要求：
Will you(please)…? Won’t you…?
Would you like to…?(用would替代will更客氣)
----Won’t you go and see the film?你不去看電影嗎？---Yes, I think I will. 不， 我想去。
2. 表示說話人的「意願」有「命令」「警告」「強制」「允諾」「決心」等，用於第二、三人稱，要重讀。
You shall do what I tell you ( to do).
我叫你幹什麼你就幹什麼。
Everything shall be done to save the ship.
一定要竭盡全力來拯救這艘船。 表示「意志」「意願」，用於各種人稱：
I won’t do anything you don’t like.
我不會做任何你不喜歡的事。
Would表示過去時間的「意志」「意願」
Shylock would not take the money earlier.
夏洛克先前是不肯要錢的。
七：used to與would用法對比表
used to would
1.表示過去的動作、狀態，重在與現在情況的對比，不一定要有時間狀語。
I used to play cards a lot, but now I seldom play.
My hometown is not what it used to be. 1.只表示過去動作的重複，有明確的時間狀語
I would go to see my grandfather on Sunday when he was in the middle school.
2.would 後只接表動作的動詞，不接表認識或狀態動詞
He used to be nervous in the exam.
2.表示過去的習慣有時可互換：
When we were very young, we used to / would go skating every winter.
2. 表示過去的次數時，不能使用：
( √）We went to the Great Wall five times when we were young.
( X ) We used to go / would go to the Great Wall five times when we were young.
註：used to do的否定式：usedn’t to do 或didn’t use to do (usedn’t也可寫作usen’t)
疑問式： Did you use to do ? Didn’t you use to do?
Used you to do? Usedn’t you to do?
情態動詞表推測
情態動詞表推測的意義：
1、大多數情態動詞（除表『能力、許可、意志』外），都可以表示推測，其程度有差異。按其可能性程度的高低排列為：
Must ﹥will ﹥would ﹥ought to ﹥ should ﹥ can ﹥ could﹥ may ﹥ might
肯定 完全可能 很可能 可能 有可能
2.注意區分情態動詞的否定的含義：
may not或許不、可能不 might not可能不 can’t 不可能
mustn’t不許、禁止 shouldn’t不應該 needn’t 不必
3.情態動詞表推測具體運用：情態動詞可以對現在、進行、過去推測
S主+情態動詞+be+adj 對「性質」「特徵」的推測
S主+情態動詞+be+n 對「職業」「事物」的推測
S主+情態動詞+V原 對經常性行為的推測
S主+情態動詞+be+V-ing 對進行著的行為的推測
S主+情態動詞+have+PP 對過去的行為的推測
特別提醒：情態動詞表推測時
1、 can只能用於否定句和疑問句
2、 must只能用於肯定句（它的否定句和疑問句其實就用can來代替了）
3、 如句中有情態動詞 + 完成時，定是對過去的推測 。
4、 句中如有表示不肯定的話語，如：I am not sure; I don’t know 之類，常選may /might的各種形式
4. 記住下面幾組表示反勸的特殊的表推測的形式
1). could + have + PP表示本來能做到，但事實上沒有做到。 He could have finished the task on time, but the heavy snow came.
2). couldn’t +have + PP表示本來不能做到，但已經做到了。 She could not have covered the whole distance, but in fact she arrived ahead of time.
3) needn’t + have + pp表示本不必做的，但已經做到了。 She needn’t have attended the meeting yesterday, but she did.
4.) should/ought to +have + PP表示 該做而沒有做 The plant is dead. I should/ought to have given ot more water.
5) shouldn’t/ oughtn’t to +have + PP表示 不該做而做了。 You oughtn’t to / shouldn’t have taken her bike without permission.
5. 記住下面對比：
must只能用於肯定句（它的否定句和疑問句其實就用can來代替了）
1.must + have + PP 表示對過去肯定的推測，譯為「一定是，準是」 The road is wet. It must have rained yesterday.
2.can + have + PP 表示對過去的推測（限於問句中） Can she have said so? 他可能這樣說嗎？
3.can’t + have + PP 表示對過去的否定推測 He cannot have said such a foolish thing.
情態動詞表推測的反意疑問句
情態動詞表推測的反意疑問句，簡單來說，就是以情態動詞後的時態為淮，如句子裡有明確的時間狀語，則以其為準。以 must 為例：
eg. 1. You must be hungry now, aren’t you?
2. He must be watching TV , isn’t he ?
3 Tom must have lived her for a long time, hasn’t he ?
4. She must have arrived yesterday, didn’t she?
註：如選擇題中（以She must have arrived yesterday, didn’t she？為例）既有didn’t she又有hasn’t she則以didn’t she？為最佳答案。
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