Modal verbs (could, should, need, etc.) always go first in the verb group. All of them, with the exception of ought, are accompanied by a verb in basic form.
I must leave fairly soon. / I have to leave very soon.
I think it will look rather nice. / I think it will look pretty good.
Things might have been so different. / Things should be so different.
People may be watching. / People can watch.
Ought is always accompanied by a verb in the form of to-infinitive.
She ought to go straight back to England. / She must go right back to England.
Sam ought to have realized how dangerous it was. / Sam should have realized how dangerous it was.
You ought to be doing this. / You should have done it.
The form
Modal verbs can have only one form. Thus, the “-s-” form for the only third person of the present tense, gerund, present participle and the simple past form of “-ed” are excluded.
There's nothing I can do about it. / I can do nothing about it.
I'm sure he can do it. / I'm sure he can do it.
In spoken and informal written English, the modal verbs shall and will be shortened to 'll. In turn, would be reduced to 'd. As such, they are added to the pronoun.
I'll see you tomorrow. / I will see you tomorrow.
I hope you'll agree. / I hope you agree.
Posy said she'd love to stay. / Posey says she really wants to stay.
The modal verbs shall, will, would never be shortened if they are at the end of a sentence.
Paul said he would come, and I hope he will. / Paul said he will come, and I hope he does.
In colloquial English, the abbreviated forms 'll and' d can be attached not only to pronouns, including nouns.
My car'll be outside. / My car will be at the exit.
The headmaster'd be furious. / The director will be angry.
When reading the abbreviation 'd, one must also remember that it is a short form for the auxiliary verb had.
I'd heard it many times. / I have heard this many times.
Time
As a rule, modal verbs do not indicate the time of occurring events. There are a few exceptions, however. For example, the modal verbs shall and will often indicate upcoming events.
I shall do what you suggested. / I will do what you suggested.
He will not return for many hours. / He will not be back in a few hours.
Could is used as a past form of can to express the ability to do something. Would be used as a past form of will to express the future tense.
When I was young, I could run for miles. / When I was young, I could run miles.
He remembered that he would see his mother the next day. / He remembered that he would see his mother next week.
Negation
To make a sentence negative, you need to place the negative word immediately after the modal verb.
You must not worry. / You should not worry.
I can never remember his name./ I can never remember his name.
He ought not to have done that. / He should not finish this.
If the negative particle at can is not reduced, then it is written as a single fused word cannot.
I cannot go back. / I can not go back.
However, if can is followed not only, then can and not do not merge.
We can not only book your flight for you, but also advise you about hotels. / We can not only book a plane ticket for you, but also give advice about the hotel.
In colloquial speech and informal English writing, not usually is shortened to n't, and the modal verbs should, could, can (may very rarely), for example, attach them at the end: could not -> couldn't, should not -> shouldn ' t, must not -> mustn't, would not -> wouldn't.
We couldn't leave the farm. / We cannot leave the farm.
You mustn't talk about Ron like that. / You shouldn't talk about Ron that way.
Modal verbs shall not, will not or cannot be abbreviated as shan't; won't; can't.
I shan't let you go. / I must not let you go.
Won't you change your mind. / You will not change your mind.
We can't stop now. / We cannot stop now.
Might not and ought not sometimes also contract, and it turns mightn't and oughtn't. It should be noted that may not very rarely used in shortened form mayn't (at least in modern English).
Question
To draw up a question, you need to put the modal verb in a position in front of the subject.
Could you give me an example? / Could you give an example?
Will you be coming in later? / Will you come back later?
Shall I shut the door? / Will I close the door?
Remember that two modal verbs are never used simultaneously in the same predicate. For example, you cannot construct a sentence like this: He will can come. Instead, say: He will be able to come.
I shall have to go. / I will need to leave.
Your husband might have to give up work. / Your husband may have to give up work.
Instead of using modal verbs, you can often use other verbs or phrases to make questions, suggestions, assumptions, express a desire, or show that your appeal is polite. For example, be able to matches can, be likely to - might, and have to - must.
All members are able to claim expenses. / All participants can file for expenses.
I think that we are likely to see more of this./ I think we are more likely to see more.
These turns can also be used after modal verbs.
I really thought I wouldn't be able to visit you this week. / I really thought I couldn’t visit you this week.
Dare and need sometimes also behave like modal verbs.
Should and ought
The modal verbs must, have to, should imply necessity, hypothetical. When you want to say what is probably true or could happen, you use should or ought. Should be accompanied by the basic form of the verb, and ought to-infinitive.
We should arrive by dinner time. / We must arrive at lunchtime.
She ought to know. / She must know.
When you want to say that, in your opinion, something is wrong or probably will not happen, should not or ought not is used.
There shouldn't be any problem. / There should not be any problems.
That ought not to be too difficult. / It should not be too complicated.
In case you need to express that you are definitely sure that this will happen, you should use should have or ought to have, accompanied by a past participle.
You should have heard by now that I'm OK. By this time you should have heard that I was fine.
They ought to have arrived yesterday. / They should have arrived yesterday.
If you want to say that you don’t think that something had a place to be, you put should not have, or ought not to have, followed by a verb in the form of the past participle.
You shouldn't have had any difficulty in getting there. / You should not have had any difficulty getting there.
This ought not to have been a problem. / That shouldn't have been a problem.
Should have or ought to have are also used to say that something you expect to happen, but has not happened yet.
Yesterday should have been the start of the soccer season. / Yesterday the football season was due to begin.
She ought not to have been home by now. / She should not have come home by this time.
Must
When you are sure that the event really takes place or happened, use must.
Oh, you must be Sylvia's husband. / Oh, you must be the husband of Sylvia.
He must know something about it. / He must know something about this.
When you are certain that the event did not happen or does not have a place to be, use cannot or can't.
This cannot be the whole story. / This may not be the whole story.
He can't be very old - he's about 25, isn't he? / He cannot be very old - he is 25, right?
In this value must not or mustn't are used.
When someone wants to say that he is almost sure of the occurrence of an event, he uses must have, which is followed by a verb in the form of the past participle.
This article must have been written by a woman. / This article must have been written by a woman.
We must have taken the wrong road. / We must have chosen the wrong path.
To describe a situation in which someone does not think that some event has taken place, he uses can't have, also accompanied by a verb in the form of the past participle.
You can't have forgotten me. / You shouldn't have forgotten me.
He can't have said that. / He could not say that.
Will
If you want to say that the event will definitely happen in the future, will will be used.
People will always say the things you want to hear. / People will always say the things you want to hear.
They'll manage. / They can handle it.
Will not or won't be used if you need to say that the event definitely will not happen or does not have a place to be.
You won't get much sympathy from them. / You don’t really put them towards you.
Other ways of expressing probability
There are several ways to outline probability and certainty without using modal verbs. For example, you can put:
1) bound to followed by a verb in basic form.
It was bound to happen. / This was bound to happen.
You're bound to make mistake. / You were doomed to make a mistake.
2) An adjective, such as certain, likely, shure or unlikely, followed by a clause with a to-infinitive as a predicate or a union that.
They were certain that you were defeated. / They were sure that you were defeated.
I am not likely to forget it. / I am not inclined to forget this.
Thus, modal verbs describe the likelihood of an action, the relationship of the actor or author to the action, they are the first in the verb group, although, as a rule, they do not take on the signs of time.