The verb have has a very wide use both independently and in conjunction with other words. In addition, there are many overlapping areas with other similar verbs.
Need to vs. have to
To talk about the need to do something, you can use the verb need to.
- You might need to see a doctor / Perhaps you need to see a doctor.
- A number of questions need to be asked. A certain number of questions must be asked.
And in contrast, to express the absence of the need to do something, don't have, don't need to, haven't got to or needn't.
- Many women don't have to work / Many women do not have to work.
- You don’t have to learn any new typing skills / You don’t have to learn any new typing skills.
- You don’t need to buy anything.
- I haven't got to go to work / I don't have to go to work.
- I can pick John up. You needn't bother / I can toss John. You don’t have to bother yourself.
In order to express permission to someone not to do anything, needn't been used.
- You needn't say anything if you don't want to / You don't have to say anything if you don't want to.
- You needn't stay any longer tonight. You don’t have to stay longer tonight.
To clarify that someone did something that was not necessary at all, use need not have or needn't have and past participles. Often such a design appeals to cases when, at the time the action was taken, the performer himself did not suspect that there was no need to commit one.
- I needn't have waited until the game began / I didn't have to wait until the game started.
- Nell needn't have worked / Nel didn't have to work.
- They needn't have worried about Reagan / They didn't have to worry about Reagan.
If the performer at the time of the action knew that there was no need for the action, then it would be more appropriate to say didn't need to. Such a clarification is explained by the fact that in the present tense we have in mind a hypothetical necessity in general, and in the past tense it is meant a specific action performed without necessity.
- They didn't need to talk about it / They shouldn't have talked about it.
- I didn't need to worry. I didn't need to worry.
Also, with the difference that if you didn’t need to, the speaker is not sure whether the incident actually took place until he receives additional information, for this you couldn’t use the modal verb have to. Examples:
- He didn't have to speak / He didn’t have to speak.
- Bill and I didn't have to pay / Bill and I didn't have to pay.
Must vs. have to
The modal verbs must, have to are sometimes used interchangeably. So, the verb have has come to the aid of must in the past tense, if you need to focus on something that should not have happened in the past. You can replace must with It was necessary, It was important not to, had to make sure, had to make certain and the like had to, the modal verb in conjunction with them means "it was important / necessary", or "important / necessary make sure".
- It was necessary that no one was aware of being watched / It was imperative that no one suspect that he was being watched.
- You had to make sure that you didn't spend too much. You should make sure that you did not spend too much.
- We had to do our best to make certain that it wasn't out of date / We had to do everything in our power to make sure that it was not outdated.
- It was important not to take the game too seriously. It was important not to take the game too seriously.
Should and ought vs. have to
Should and ought can be used to talk about moderate necessity, that is, the feeling of necessity is not as strong as if we used must.
Should and ought are very common in spoken English. Should, being a truly modal verb, requires the use of the subsequent verb in basic form. And ought requires a to-infinitive. Denial with these verbs looks like should not, shouldn't, ought not, oughtn't and means that there is a moderate need not to do anything.
There are three cases in which should, ought is put:
1) When it comes to the performance of any positive or correct action.
- We should send her a postcard. / We must send her a postcard.
2) When you want to advise someone to do something or not to do.
- You should claim your pension 3-4 month before you retire. / You must apply for retirement 3-4 months before leaving.
3) When you express your point of view or ask someone else's opinion. At the same time, in order to start a sentence, the following are often used: I think, I don't think, or Do you think.
- I think that we should be paid more. / I think we should pay more.
Try to distinguish between cases where should, ought and the modal verb have to are used. The exercises below contain omissions, fill them out:
- We _______ spend all the money. / We do not have to spend all the money.
- He ______ come more often. / He should come more often.
- You ______ see him again. / You should not see him again.
- You ______ use a detergent. / You should not use detergent.
- You ______ get a new TV. / You need a new TV.
- You ______ marry him. You should not marry him.
- I don't think we ______ grumble. / I do not think we should complain.
- Do you think he ______ go? / Do you think he should not go?
- What do you think we ______ do? / What do you think we should do?
To say that in the past there was a moderate need to do something, but the action was not completed, the following are used: should have or ought to have with the past participle. For example, if I should have given him the money yesterday, it means that there was a moderate need to transfer money yesterday, but the money was not transferred.
- I should have finished my drink and gone home. / I had to finish my drink and go home.
- You should have realized that he was joking. / You should have understood that he was joking.
- We ought to have stayed in tonight. / We had to stay that night.
- They ought to have taken a taxi. / They had to call a taxi.
If you want to say that it was important not to do something in the past, but nevertheless it was done, should not have, ought not to have. For example, if it says: I should not have left the door open, it is understood that it was important that someone did not leave the door open, but the door nonetheless remained open.
- I should not have said that. / I should not have said that.
- You should not have given him the money. / I should not have given him money.
- They ought not to have told him. / They should not have told him.
- She oughtn't to have sold the ring. / She should not have sold the ring.
Had better
Had to was used to indicate a moderate need to do something in a particular situation. In this case, the modal verb loses to and is added better, forming a had better, accompanied by the verb in the basic form. Also, had better can be used to give advice or to express one’s point of view on any issue. Although usually a negative particle is placed immediately after had to, the modal verb and not in this case are better separated. The negative form looks like had better not.
- I think I had better show this to you now. / I think it's better to show you this now.
- You'd better go tomorrow. / You better go tomorrow.
Although had better resembles the past tense, it is never used for moderate necessity in the past. Moreover, the correct form is always had better (they do not say have better).
- I'd better not look at this. / I better not look at that.
Thus, in the range of values, there are many separate semantic units, which far from always behave according to the general logic. For example, had to (the modal verb have to in II form) does not always indicate the past tense.