The verbs must, have to, should, ought to, need, be to are modal verbs of obligation. They express meanings such as obligation, necessity, lack of necessity, certainty, offers, requests, logical assumption, prohibition, advice or criticism.
Modal verbs:
- Do not take an – s, — ing, or – ed suffix.
- Are followed by a bare infinitive (except for ought to, have to, be to).
- Go before the subject in questions and are followed by not in negations.
- Do not usually have tenses (except for should/shouldn’t, ought to/ ought not to, needn’t)
MUST (past and future have to, be to)
We use must
- 1. To say that it is necessary to do smth. The speaker is giving his own feelings, saying what he thinks is necessary:
e.g. You don’t see anything. It can be dangerous. You must wear glasses. (The speaker personally feels that it is necessary)
2. For giving strong advice to ourselves:
e.g. I must try to go to bed early tonight. (It is the person’s inner feeling that it is necessary to do)
3. For making strong recommendations, offers and invitations to others, based on our own opinions:
e.g. You must visit London, it’s a gorgeous city!
You must behave yourself at school.
4. For stating rules, obligation, smb’s duty (especially in formal and written English):
e.g. Cyclists must wear helmets.
You must stop when the traffic light is red.
5. In questions to clear up whether the person insists on the speaker’s doing smth. Has a negative connotation.
e.g. Mom, must I do my homework now? (The boy wants to know whether the mother insists on his doing his homework right now. He isn’t very happy about it) – Мне что, делать уроки сейчас?
6. In negation to express prohibition we use mustn’t which means that it is necessary that smb. do not do smth.
e.g. You mustn’t tell anyone what I said. (It is necessary that you don’t tell anybody else)
You mustn’t feed the animals in the Zoo. (it is forbidden)
HAVE TO(requires do /does/ did to make questions and negations)
We use have to
- 1. To say that it is necessary to do smth. But the speaker isn’t giving his own feelings. He is just giving facts:
e.g. Ann’s eyes are not very good. She has to wear glasses.
2. For obligation (NB! We use I have to … for things that are obliged to; we use I must … for things that we strongly feel we should do.):
Cf. I must start cycling to work. It would be good experience.
I have to start cycling to work. They’ve cancelled the only bus.
3. In negation don’t /doesn’t have to means that it is not necessary to do smth.:
e.g. You don’t have to do it if you don’t like it. (but you may)
Syn. Needn’t do
e.g. You’ve got plenty of time. You needn’t (don’t have to) hurry.
4. In questions to ask smb. if it is necessary for you to do smth.:
e.g. Mom, do I have to do my homework now? (Is it necessary to do your homework now or can you do it some other time?)
SHOULD /OUGHT TO (Past – should /ought to have done — reproach)
- 1. For giving advice:
e.g. We should/ ought to invite Sue to the party. (Нам стоит пригласить…)
2. For asking for or giving an opinion about smth. It is often used in sentences beginning with I think…
e.g. I don’t think you should/ ought to work so hard. (Я думаю, тебе не стоит так много работать)
Do you think I should/ ought to apply for this job? (Ты думаешь, мне надо…?)
3. To say smth. is not ‘right’ or not what we expect:
e.g. The price here is wrong. It says 65 pence but it should be 50.
Those children shouldn’t be playing. They should be at school.
4. For expressing duty (less emphatic than must)
e.g. People should /ought to take better care of the environment. (We think it’s the right thing to do)
5. In the past should have done / ought to have done for criticising or reproaching smb., for saying that smb. did the wrong thing in the past:
e.g. – Hello, Ann. The party last night was great. And we all waited for you to come but you never did. You should have come.
They shouldn’t have listened to our conversation. It’s private. (Не следовало ….)
Cf: didn’t have to do smth – не было необходимости и человек не делал;
needn’t have done smth – можно было и не делать, но человек сделал;
shouldn’t have done smth – не стоило делать чего-то, но человек сделал и есть отрицательные последствия этого действия
e.g. She didn’t have to get up early yesterday as it was Sunday, so he stayed in bed till 10.
She needn’t have got up early yesterday as it was Sunday but she forgot and at 7 her alarm clock went.
You shouldn’t have told her about it yesterday as she was worrying the whole night.
TO BE TO (to express the action in past and in future)
- For preliminary arrangements or duty:
e.g. We are to meet at 6.
Who is to arrange the meeting?
- For giving orders (more categorical than must):
e.g. You are not to leave the house today. = Не смей выходить сегодня из дома!
The chief says I am to be in charge of the programme.
- For expressing smth. inevitable:
e.g. He didn’t know at that time that he was never to see his son again.
4. For expressing a possibility due to circumstances:
e.g. Where is he to be found?