have to後面的動詞用什麼形式
have to後跟動詞原形，表示客觀需要做的事情，意思是“必須”、“不得不”，有人稱、時態和數的變化，與情態動詞 must 近義。
一、 have to 的陳述句形式
A、 肯定式：have to + 動詞原形
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) + have to + 動詞原形
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.
他不必整天呆在家裏。
二、have to 的一般疑問句形式及簡略答語
have to的一般疑問形式必須藉助助動詞 do 或 does：
1、 Do you have to look after your sister?
你得照看你妹妹麼？
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麼?
Yes, he does. / No, he doesn't.
是，他必須做。/不，他不必做。
三、have to 的特殊疑問句形式
1、 What do you have to do on Sundays?
在星期天你得幹什麼？
2、 Why does she have to move to Paris?
她爲什麼得遷往巴黎？
3、 Where do they have to work?
他們必須在哪裏工作？
四、have to 可用於各種時態
A、一般現在時：
I have to visit Mr Wang tomorrow.
明天我得去拜訪王先生。
B、一般過去時：
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,因爲沒有公共汽車。
C、一般將來時：
We'll have to ask Zhang Ming instead.
我們得請張明代替。
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裏幫他爸爸幹活。
五、have to 與 must 的用法區別
A、 have to 比較強調客觀需要，而 must 着重說明主觀看法。
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。
B、 have to 有時態和人稱變化，而 must 則沒有。
1、 Mary has to water the trees.
瑪莉得澆樹。
2、 He must bring a picnic tomorrow.
他明天得帶野餐。
C、must 有“推測”之意，而 have to 則沒有。
He must be in the classroom.
他一定在教室裏。
