華閱文章網1.含有情態動詞must的句子變否定句怎么變
must 有非推測性用法和推測性用法兩種情態意義，變否定句的方法不同。
▲非推測性用法的must表示義務，情態意義為“必須”。
He must finish his homework before bedtime. 他必須在上床前寫完作業。
此用法的must兩種否定形式：
1. 結構上否定：在must改為must not或mustn't，情態意義為“不許”。
He mustn't finish his homework before bedtime. 不許他在上床前寫完作業。
2. 意義上否定：將must改為need not或needn't，情態意義為“不必”。
He needn't finish his homework before bedtime. 他不必在上床前寫完作業。
▲推測性用法的must表示必然，情態意義為“肯定”。
He must finish his homework before bedtime. 他肯定在上床前寫完作業。
此用法的否定形式為can't，情態意義為“不可能”。
He can't finish his homework before bedtime. 他不可能在上床前寫完作業。
2.英語,含有系動詞的陳述句變否定句
第一種情況：
要看句中謂語動詞是否有系動詞（is /am/are/was/were）或者情態動詞（can/may/must/should/would/could/will/shall/need）.以上兩種情況只要符合其中之一，就在其系動詞或者情態動詞后直接加not即可（也可以用其縮略式）
其具體結構為：
主語+系動詞/情態動詞+not /縮略式+V（原形） +其他。
注意：如果句中含有并列詞and時，變為否定句后要改為or。
例句：
* twins are watching TV now.
The twins arenot(aren't) watching TV now.
* were in the front of the classroom.
They werenot(weren't) in the front of the classroom.
* child can play the piano very well.
The child cannot(can't)play the piano verywell.
* students should help each other in study .
We students shouldnot(shouldn't) help each other in study.
第二種情況：
如果句中謂語動詞既無系動詞又無情態動詞而是實義動詞，則要用助動詞do或者它的其他形式does/did+not（或者用其縮略式don't/doesn't/didn't）即可。
其具體的結構為：
主語+do/does/did+not+v原形+其他。
注意：如果句中含有并列詞and時，變為否定句 后要改為or。
* always go to school on foot every day.
We always don'tgo toschool on foot every day.
* went to the hospital to see their good friend, Tom.
They didn'tgo tothe hospital to see their good friend ,Tom.
* good friend has two eggs and a glass of milk in the morning beforehe goes to school.
My good friend doesn'thave twoeggs or a glass of milk inthe morning before he doesn'tgo toschool .
3.含有be動詞和情態動詞的句子,怎么變否定句和一般疑問句
改成否定句方法：
1、找到be動詞或是情態動詞
2、在后面加上not
改成一般疑問句方法：1、找到be動詞或是情態動詞
2、把be動詞或是情態動詞提前
3、其余照抄
例子：
(1)You are(be) a student.
改成否定句，在be動詞后面加not
You are not a student.
改成一般疑問句，把be動詞提前
Are you a student?
(2)You can do it.
改成否定句，把情態動詞can后面加上not
You can not do it.
改成一般疑問句，把情態動詞can提前
Can you do it?
4.含有助動詞的句子
1、助動詞be(am, is, are, was, were, being, been)的用法 （1） be后跟現在分詞構成進行時態。
Who is playing the violin？誰在拉小提琴？She was reading a book then.那時她正在讀書。（2）be后跟過去分詞構成被動語態。
He was asked to do the work.有人要他干這件工作。You are invited to attend the meetintg.有人邀請你參加會議。
（3）be 后跟不定式作謂語，有如下幾種情況：①表示計劃、安排將要發生的事。Who are we to meet？我們要見誰呀？I'm to have supper with John this afternoon.今天下午我要與約翰一起吃晚飯。
②表示指示、命令，否定式表禁止。You are to see the headmaster today.今天你必須去見校長。
You are not to enter the room without permission.未經允許你不能進入房間。③表示義務、責任等，同should。
You are to be back before 5.你得在5點鐘以前回來。What is to be done？該干什么。
④表示可能性，與情態動詞may, can同義。Such books are to be found in any library.這種書任何圖書館都有。
Not a sound was to be heard.一點聲響也沒有。⑤表示后來發生的事，可以用來表示命運或注定 They say good-bye, little knowing that they were never to meet again.他們告別了，沒想到再也不能相見了。
He was to regret the decision.他有一天會后悔做出這一決定的。⑥用于習語 Where am I to go？ 我該向何處去？What am I to do？ 我該怎么辦？2、助動詞have(has, had, having)的用法 （1）助動詞have可以構成完成時或完成進行時 He has been a doctor for 10 years.他當醫生十年了。
This is the place I have been longing to visit.這就是我一直渴望參觀的地方。（2）和不定式構成謂語，表示客觀上不得不做的事情。
We've missed the train. We'll have to wait for another one.我們己經誤了火車，我們只能等下一列。-Do we have to start work？我們得立刻工作嗎？-No. We don't have to.不，不必了。
3、do(does, did) 的用法 （1）構成疑問句或否定句 How did you know about it？你是怎樣知道這件事的。He does not smoke. 他不抽煙。
（2）加強語氣。He did tell that.他的確告訴了此事。
Do come and see us.一定來看我們。（3）代替前面剛出現的動詞，避免重復。
-You like popular music, don't you？你喜歡流行音樂，是吧？-Yes , I do.是的，我喜歡。He speaks French as fluently as she does.他講法語和她講的一樣流利。
（4）用于倒裝句中。Never did he pay attention to my words.他從不注意我的話。
Only then did I understand the importance of English.只是那時，我才了解到英語的重要性。（5）構成否定的祈使句。
Don't be so careless.不要那么粗心。Do not hesitate to come for help.只管來求助。
4、shall(should)和will(would) 的用法 （1）shall(should)用于第一人稱的將來時中，單純表示來 I shall think it over.我要好好考慮一下。When shall I see you again？我何時再見到你？I rang up to tell her that I should leave for London. 我打電話告訴她我要去倫敦。
（2）will用于第二、第三人稱的將來時態中，在現代英語中可以用于所有人稱 He will be 30 next month. 他下月將是30歲。You will have an English test tomorrow.明天你有英語小測驗。
He wanted to know when you would finish the writing.他想知道你何時完成寫作。
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