Auxiliary Verbs: A brief Description: Uses of Modal Verbs

English verbs are classified into two major classes.
(i) Lexical Verbs
(ii) Auxiliary Verbs

(i) Lexical Verbs: Lexical verbs are also known as ordinary verbs. They have independent means and are used as main verbs in a sentence. They have v1, v2, v3, v4(-ing), and v5(-s/es) forms.
Ex - Ram eats a mango.
        He is running.
        What do you want? 

(ii) Auxiliary Verbs: The verbs that help main verbs to form Tense, Mood, Voice and required expressions is known as Auxiliary Verbs.
Ex - I am going. 
        He has eaten.
        It might rain today.

Note: Auxiliary verbs such as am, is ,are, have, has etc. are used as main verb in independent way in a sentence. Again Auxiliary verbs such as be, do, have, need and dare are also used as Lexical verbs.
Ex - I am a boy. (am - main verb)
        He has a car. (has - main verb)
        He is doing the work. (doing - lexical verb)
        What do you have? (have - lexical verb)

Kinds of Auxiliary Verbs: 

According to the uses and structure, Auxiliary verbs are divided into three parts.

(i) Primary Auxiliary Verbs: Verb to be like - be, am, is, are, was, were, been, being; verb to have like - have, has, had, having and verb to do like - do, does, did are known as Primary Auxiliary Verbs.

(ii) Modal Auxiliary Verbs: Can, could, may, might, shall, should, will, would, must, ought to are called Modal Auxiliary Verbs. 

(iii) Marginal Auxiliary Verbs: Used to, dare and need are called Marginal or Semi Modal Auxiliary Verbs.

Some Important Facts of Auxiliary Verbs: 

(i) Modal Auxiliaries are used as helping verbs not as main verbs.

(ii) Modal Auxiliaries do not have v1, v2, v3, v4 and v5 forms. They are used as the same form with all the numbers and persons.

(iii) Generally there is M.v1(first form of main verb) after the Modal Auxiliaries. It means we can not use infinitive with 'to'.

Ex - I can go. (Correct)           (go - v1)

        I can to go. (Incorrect)   (to go - infinitive with to) 

(iv) Infinitive with 'to' is used after ought and used. 

Ex - We ought to help the poor.   ( Correct)

        We ought help the poor.        ( Incorrect)

(v) Dare and need are used as main verbs.

Ex - He needs my help.

        He does not dare to go there.

(vi) Verb to be is used as M.v4(present participle) in Continuous Tense.

Ex - He is taking coffee.

(vii) Verb to be is used as M.v3(past participle) in Passive Voice.

Ex - A letter was written by me.

(viii) Verb to be is used before the v3(past participle) of Intransitive verbs in Passive voice.

Ex - The sun has come out.

        Summer is gone.

(ix) Do is used to make negative of an Imperative sentence and to form an Emphatic sentence.

Ex - Don't go there.

        Do sing it again.

Uses of Modal auxiliaries: 

A. Use of Can: 

(i) Can is used to express power, ability and capacity.

Ex - He can lift the box.               ( power)

        You can speak English.        ( ability)

        We can climb Mount Abu.  ( capacity)

(ii) Can is used to express permission.

Ex - You can go now.

        Can i see your diary?

Note: To express Permission, the use of 'May' is better than the use of 'Can'.

(iii) It is used to express theoretical possibility.

Ex - Everyone can make a mistake.

        It can't be true.

(iv) It is used to express habit or nature.

Ex - A deceitful person can deceive us.

       An honest man cannot harm anyone.

B. Use of Could: 

(i) Could is used as the past tense form of can in Indirect Speech.

Ex - He said that he could beat me in the race.

(ii) It is used to express past ability/power/capacity.

Ex - My brother could drive a car at age of sixteen.

        He could pass the Board examination.

(iii) It used to express Polite request/permission in Interrogative Sentences.

Ex - Could you help her, please?

        Could I smoke here?

(iv) It is used to express Possibility in the sentences expressing unreal situation of present.

Ex - If I had more money, i could buy a motor cycle.

        If you worked hard, you could succeed.

C. Use of May: 

(i) May is used to express to take or give permission.

Ex -1 Q. May I use your mobile?

         A. Yes, you may.

Ex - 2 You may go now.

(ii) It is used to express Possibility/ uncertainty. 

Ex - It may rain today.

        I may buy a car this year.

(iii) It is used to express wish/pray/bless/curse.

Ex - May you live long!

        May you have a happy and long life!

(iv) If the Principal Clause is in Present Tense and the Subordinate Clause starts with that/so that/in order that, then may is used in the Subordinate Clause.

Ex - I work hard that/so that/in order that I may succeed.

        We eat that we may live.

(v) It is used to express uncertainty/surprise.

Ex - How old she may be!

        Who may be there!

Use of Might: 

(i) Might is used as the past tense form of may in Indirect Speech.

Ex - He said that I might go then.

(ii) It is used to express less possibility.( May is used to show more possibility.)

Ex - It might rain today.

        She might come late.

(iii) It is used to express polite request/permission.

Ex - Might I ask a question?

        You might make a little less noise.

(iv) It is used in the clause expressing suppositional sentence.

Ex - If you worked hard, you might succeed.

        I wish he might have seen 'Mother India'.

Use of Shall: 

(i) Shall is used with first person I and we in Future Tense.

Ex - I shall go to Patna tomorrow.

        We shall go there tonight.

Note: It is also used with second and third person to express command, promise, threatened, determination and compulsion.

Ex - He shall go there at once. (command)

        They shall be awarded. (promise)

        She shall be punished if he does that again. (threatened)

        He shall obey me. (determination)

        You shall come to school at ten. (compulsion)

(ii) It is used in the question tags of Imperative Sentences starting with Let us/Let's.

Ex - Let us dance together, shall we? 

        Let's play, shall we? 

(iii) It is used with the subjects of first person in interrogative sentences expressing suggestions.

Ex - Shall we talk to the headman?

        Shall I open the gate?

(iv) It is used with the subjects of first person in interrogative sentences expressing simple futurity, permission or desire.

Ex - Shall I be wasting in despair? (simple futurity)

        Shall we go out? (permission)

        Shall I thread the needle for you? (desire)

(v) It is used with the subjects of first person in interrogative sentences expressing orders, instructions and speculations.

Ex - What shall I do for your children, sir?

        What shall I do in month?

Use of Will: 

(i) Will is used with Second and Third Person in future tense.

Ex - You will go to London tomorrow.

        He will help her.

Note: It is also used with first person to express determination, promise, threatening and willingness.

Ex - I will not surrender before the judge. (determination)

        We will try to help you in the examination. (promise)

        We will spoil you. (threatening) 

        I will go to Rajgir with my wife. (willingness) 

(ii) It is used with the subjects of second and third person in interrogative sentences to get information.

Ex - Will you buy a radio set today?

(iii) It is used to express invitation, request, instructions, orders and inevitability.

Ex - Will you come to dinner? (invitation)

        Will you help me? (request)

        Bring a glass of water, will you? (instruction)

        You will do it anyway. (order)

        Accidents will happen. (inevitability)

Use of Would: 

(i) Would is used as the past form of will in Indirect Speech.

Ex - He said that he would go there.

(ii) It is used to express past habit.

Ex - He would go for a walk every morning.

(iii) It is used to express polite request in Interrogative sentences.

Ex - Would you please lend me your book?

(iv) It is used to express Probability.

Ex - He would be a farmer.

(v) It is used to express wish.

Ex - Would that he were her. (Like - I wish that he were here.)

Note: Would like to is also used to express wish.

Ex - He would like to know what his future is.

(vi) It is used to express determination.

Ex - He would not lie.

(vii) It is used to express past willingness.

Ex - I would do as you bid.

(viii) It is used to express preference or choice.

Ex - He would rather die than tell a lie.

        He would die as soon as beg.

(ix) It is used in the Principal clause of a sentence expressing present or past unreal conditions. 

Ex - If I were a bird, I would fly in the sky.

        I would go there, if I were allowed.

(x) It is used to express refusal.

Ex - The machine wouldn't start.

Use of Should: 

(i) Should is used as the past form of shall in Indirect Speech.

Ex - I said that I should not do that work.

(ii) It is used to express moral obligation or duty.

Ex - We should not tell a lie.

        One should love one's country.

(iii) It is used to give advice.

Ex - You should not laugh at his mistakes.

(iv) It is used to express supposition.

Ex - If it should rain, they will not come.

(v) It is used to express possibility.

Ex - I think he should come tomorrow.

(vi) It is used to express purpose and result in the clause starting with so that/in order that.

Ex - We did it carefully so that one should see it.

(vii) It is used to express negative purpose after lest.

Ex - He ran fast lest he should miss the train.

(viii) It is used to express determination, willingness, threats, orders or promises after the verbs or phrases in subordinate clause.

Ex - I promised my son that he should have a new book.

        I have ordered that he should play today.

(ix) It is used to express formal notices or instructions.

Ex - Candidates should answer all the questions.

(x) It is used to express condition.

Ex - Should he not come, what shall we do?

(xi) It is used to express polite advice or improvement in the Principal Clause of a sentence expressing unreal situation.

Ex - If he were you, he should not do it.

        If I were you, I should not cheat him.

Use of Ought to: 

(i) Ought to is used to express moral obligation desirability or duty.

Ex - We ought to love our country.

        Students ought to work hard.

(ii) It is used to express strong probability.

Ex - He ought to win the race.

(iii) It is used to express logical necessity.

Ex - Aditya ought to start at once.

(iv) It is used to express advice.

Ex - You ought to read the Bible. 

(v) Ought to + have + M.v3 is used to express past obligation.

Ex - He ought to have worked hard.

You ought to have helped her.

(vi) Ought not to + have + M.v3 is used to express past disapproval.

Ex - You ought not to have laughed at her mistakes.

Use of Must: 

(i) Must is used to express compulsion or strong moral obligation.

Ex - Candidates must answer at least five out of the ten questions.

(ii) It is used to express fixed determination.

Ex - We must go. 

         I must have my money back.

(iii) It is used to express duty.

Ex - A judge must be upright.

(iv) It is used to express certainty.

Ex - We must win this match.

(v) It is used to express strong likelihood.

Ex - He must be hungry after his long walk.

(vi) It is used to express inevitable.

Ex - Students must work hard to get 80%marks.

Use of Used to: 

(i) Used to is used to express past habit/situation.

Ex - He used to walk in the morning.

(ii) It is used to express discontinued habit.

Ex - He used to drink beer; now he drinks wine.

Use of Need: 

(i) Need is used as main verb in both singular and plural form to mean require/to have to be necessary.

Ex - He needs my help.

        I need a book.

(ii) Need not or needn't is used as marginal auxiliary in plural form to express a negative idea.

Ex - I need not go there.

        He need not come here.(correct)

        He needs not come here. (incorrect)

Use of Dare: 

(i) Dare is used as main verb in both singular and plural form to mean to be courageous enough to do something or to have the impudence.

Ex - He dares to go there.

(ii) Dare not or daren't is used as marginal auxiliary in plural form to express a negative idea.

Ex - I dare not go there.

Worked Out Examples: 

(i) ..... I go out, sir. 

(ii) It ..... be true. 

(iii) We .... love our country.

(iv) Boys .... be boys. 

(v) Who .... be your enemy here?

(vi) This ....not be true.

(vii) Teachers .... be at their tables by 10 a.m.

(viii) The deaf .... not hear.

(ix) Work hard lest you .... fail.

(x) I .... unable to support you.

[ Ans: May, may, should, will, may, can, must, can, should, am ]