Question

have to与come back 的用法

Answer 1

have to 英[ˈhæv tə] 美[hæv tu]
不得不，只好;只得;必须;不得已
[例句]You have to stay in the solution.
你必须坚持拿出对策解决问题。

come back 英[kʌm bæk] 美[kʌm bæk]
回来;记起;强烈反驳;<非正>重复说
[例句]All my friends and relatives say , ' don 't come back.
“我的朋友和亲戚们都说：‘别回来了。

以下资料来自网络
一、have作实意动词。
1.表示“有”的意思。
Look, I have wings, just like you. (JBⅤL1)
He had fair hair and blue eyes. (JBⅥL2) 〔注1〕：其否定和疑问形式变化，在美国通常用助动词do。
〔注2〕：在英国口语中常用have got代替have.
Look, can’t you see I've got teeth, too,(JBⅤL1)
I haven't got any jewelry.(SBⅠL5)
2.have和一些其他名词连用，表示：
(1)一种活动。
We have no classes on Sunday.（上课）(JBⅡL11)
they’re going to have a volleyball match.（举行比赛）(JBⅢL11)
Are we going to have a meeting this week?（开会）(JBⅢL11)
We are going to have a talk this afternoon.（听报告）(JBⅢL11)
(2)患病。
I have got a headache.(JBⅣL8)
I have a bad cold.(JBⅤL3)
(3)发生的情况。
I've had so many falls that I'm black and blue all over.（跌跤）(JBⅣL10)
(4)生育。
The queen ant may have tens of thousands of babies in one summer.(SBⅠL14)
3.和一与动词同形的名词连用，表示一个动作（have＋a＋由动词转化和名词）。
Are you going to have a swim.(JBⅢL1)
I have a long talk with the teacher.(JBⅣL10)
4.have on sth.或have sth. on，表示“穿着”、“戴着”(=to be wearing)。
I noticed he had on bedroom slippers.(SBⅡL6)
At the ball Motile had a diamond necklace on.
5.表示“吃”、“喝”。
I wanted to have a cup of tea and some eggs.(JBⅢL10)
Does she have lunch at home?(JBⅡL11)
6.组成复合结构即“have＋宾语＋宾语补足语”。
(1)不加to的动词不定式作宾语补足语(have sb. do sth.)，表示让、叫某人做某事。
The soldier had him stand with his back to his father.(SBⅠL17)
〔注〕：否定结构表示“不能让…”或“从未有人…”.
We won't have you blame it on others.
She had never had anybody speak to her that way before.
(2)现在分词作宾语补足语(have sb.(sth.)doing)，表示让（使）某人做某事。
…the two men had their lights burning all night long….
(3)过去分词作宾语补足语(have sb. (sth.)done)，表示：
①使（让，请）别人作某事，表示的动作是别人做的。
Emperor Qin Shi Huang had all the walls joined up.(SBⅠL10)
…he should have new clothes made of this splendid cloth for the coming great procession.(SBⅠ L8)
②遭遇到某事。
Houses near airports sometimes have their windows broken.(SBⅠL12)
Workers in some industries have their hearing harmed by the noise of the machine.(SBⅠL12)
二、have与to一起构成情态动词，表示“不得不”、“必
须”，可用于各种时态。
I have to look after her at home.(JBⅢL4)
三、have做助动词与动词的过去分词一起构成现在完成时
和过去完成时。
Great changes have taken place the last two years.(JBⅥL3)
They said that the Arab had stolen their camel.(JBⅤL4)
四、have用于“情态动词＋have＋过去分词”的结构，有
推测、假设之意。
1.must＋have＋过去分词，表示对过去时间发生的动作或存在的情况的推测，一般用于肯定句。
Her father thought that she must have met a fairy.(SBⅠL10)
You must have left your bag in the theatre.
2.can(could)＋have＋过去分词，表示对过去发生事情的“不肯定”，常用于否定句和疑问句。
He can't have been to your home, he doesn't know your address.
3.should＋have＋过去分词，表示“某事本该早做而实际未做”，用于肯定句。
You should have been here five minutes ago.(SBⅡL10)
五、have用于某些成语，表示固定的意思。
1.have a word(a few words)with sb.，表示和某人说一（几）句话。
Where's Peter? I want to have a word with him.(SBⅢL13)
2.had better＋不带to的动词不定式，表示“…最好…”。
I'd better go and look for him now.(JBⅢL2)
3.have nothing(something)to do with，表示“和…无（有）”关系。
Most of questions had nothing to do with Edison's lessons.

关于have to的补充：

have to通常指由于客观原因则不得不做某事，意思为“不得不”。

e.g. It's dark now. I have to go home.

天黑了，我不得不回家。

It's raining, and I have to stay at home.

外面在下雨，我不得不呆在家里。
一、have to与一般情态动词的异同

相同点：

一般的情态动词不能单独作谓语，后面必须接动词原形一起构成谓语，have to 也是这样。

不同点：

1、一般的情态动词没有人称和数的变化，而且所用的时态也受到一定的限制，而have to 有人称和数的变化。可用于多种时态中：一般现在时中当主语是第三人称单数时要用has to，其余的人称用have to，一般过去时中要用had to； 一般将来时中则要用will have to.

e.g. She has to go to school by bus.

她不得不乘公汽上学。

You'll have to see the doctor if you get ill.

如果你生病了，就得去看医生。

2、否定句和疑问句的构成方式不同：

①一般的情态动词直接在后面加not构成否定句，把这些情态动词提到句首就构成一般疑问句。

②而have to 的否定句和疑问句的构成往往要借助于助动词do的适当形式或助动词will即have to, has to, had to和will have to的否定式分别为don't have to, doesn't have to, didn't have to和won't have to，疑问句是在句首加助动词do的相应形式，句中还原成have to或把will放到句首，这里have to简直就是一个十足的行为动词。

e.g. What does she have to do?

她必须做什么？

You didn't have to wait for me yesterday.

昨天你没有必要等我