have to表示客觀需要做的事情,意思是“必須”、“不得不”.后跟動(dòng)詞原形,有人稱(chēng)、
時(shí)態(tài)和數(shù)的變化,與情態(tài)動(dòng)詞 must 近義.
一、 have to 的陳述句形式
A、 肯定式：have to + 動(dòng)詞原形
1、 I have to tidy my room.我得整理房間.
2、 She has to help with the washing.她得幫忙洗衣服.
B、 否定式：don't (doesn't) + haveto + 動(dòng)詞原形
1、You don't have to go if you don't want to.如果你不想去,你就不必去.
2、He doesn't have to stay at home all day.他不必整天呆在家里.
二、have to 的一般疑問(wèn)句形式及簡(jiǎn)略答語(yǔ)
have to的一般疑問(wèn)形式必須借助助動(dòng)詞 do 或 does：
1、 Do you have to look after your sister?你得照看你妹妹么?
Yes,I do./ No,I don't.是的,我得照看./不,我不必照看.
2、 Does Jim have to do his homework?吉姆必須做家庭作業(yè)么?
Yes,he does./ No,he doesn't.是,他必須做./不,他不必做.
三、haveto 的特殊疑問(wèn)句形式
1、 What do you have to do on Sundays?在星期天你得干什么?
2、 Why does she have to move to Paris?她為什么得遷往巴黎?
3、 Where do they have to work?他們必須在哪里工作?
四、haveto 可用于各種時(shí)態(tài)
A、一般現(xiàn)在時(shí)：I have to visit Mr Wang tomorrow.
明天我得去拜訪王先生.
B、一般過(guò)去時(shí)：That night we had to walk home because there was no bus.
那天晚上我們不得不步行回家,因?yàn)闆](méi)有公共汽車(chē).
C、一般將來(lái)時(shí)：We'll have to ask Zhang Ming instead.
我們得請(qǐng)張明代替.
D、與may 連用：I think he may have to help his Dad in the garden.
我想他可能得在花園里幫他爸爸干活.
五、have to 與 must 的用法區(qū)別
A、 have to 比較強(qiáng)調(diào)客觀需要,而 must 著重說(shuō)明主觀看法.
1、 My mother is ill.I have to look after her at home.
媽媽病了,我得在家照看她.
2、 You must finish your homework first.
你必須先完成作業(yè).
B、 have to 有時(shí)態(tài)和人稱(chēng)變化,而 must 則沒(méi)有.
1、 Mary has to water the trees.
瑪莉得澆樹(shù).
2、 He must bring a picnic tomorrow.
他明天得帶野餐.
C、must 有“推測(cè)”之意,而 have to 則沒(méi)有.
He must be in the classroom.
他一定在教室里.