Unit 3: Modals - Subjective Questions

Modal verbs are auxiliary verbs that express meanings such as ability, possibility, permission, obligation, necessity, advice, prediction, or willingness. Common modal verbs include can, could, may, might, must, shall, should, will, and would.

They differ from ordinary lexical verbs in the following ways:

• They do not usually take -s in the third-person singular: She can swim, not She cans swim.
• They are followed by the base form of a verb: He must study.
• They form questions by inversion: Can you help me?
• They form negative sentences by adding not: You should not worry.
• They do not normally use do, does, or did for questions and negatives.
• They express the speaker's attitude toward an action rather than naming the action itself.

The general structure of a sentence containing a modal verb is:

Subject + modal verb + base form of the main verb + object or complement

Examples:

• She can speak French.
• They must complete the assignment.
• We should respect our elders.

Important structural rules include:

• A modal verb is followed by the bare infinitive, or base form, of the main verb.
• The modal does not change according to the subject.
• A modal verb is followed directly by the main verb without to: He can drive, not He can to drive.
• In negative sentences, not follows the modal: You must not enter.
• In questions, the modal comes before the subject: Should I call you?

Can and could are used to express ability, possibility, permission, and requests, but they differ in time and degree of politeness.

• Can expresses present ability: Rina can solve difficult problems.
• Could expresses ability in the past: Rina could solve difficult problems when she was a student.
• Can may express present or general possibility: This road can be dangerous at night.
• Could often expresses weaker or less certain possibility: It could rain this evening.
• Can is used for informal permission: Can I borrow your book?
• Could is used for more polite requests: Could you explain the answer?
• Could may also describe a possible condition: If we leave early, we could reach the station on time.

Thus, could can indicate past ability, politeness, or a less certain possibility.

May and might are both used to express possibility and permission, but their meanings are not always identical.

• May generally expresses a stronger possibility: The teacher may announce the results today.
• Might generally expresses a weaker or more uncertain possibility: The teacher might announce the results today.
• May is commonly used to ask for or give formal permission: May I come in?
• Might is rarely used for present-day permission, although it can occur in very formal or traditional expressions.
• Might can refer to a possible past situation when used with a perfect infinitive: She might have missed the bus.
• May can express a wish in formal language: May you succeed in your examination.

Both verbs are followed by the base form of the main verb, as in may go and might go.

Must is used mainly to express strong obligation, necessity, logical conclusion, and prohibition when combined with not.

• Strong obligation: Students must attend all practical classes.
• Necessity: You must submit the form before Friday.
• Logical conclusion: The lights are on, so someone must be at home.
• Prohibition: You must not use a mobile phone during the examination.

The structure is generally:

Subject + must + base verb

For example, Employees must follow the safety rules.

The negative form must not means that an action is prohibited. It does not usually mean that an action is unnecessary. To express lack of necessity, use need not or do not have to, as in You need not bring a notebook.

The expressions must, have to, and need not all relate to necessity, but they are used differently.

• Must usually expresses an obligation felt by the speaker or an obligation presented as especially important: You must revise this chapter.
• Have to usually expresses an external obligation caused by a rule, law, schedule, or circumstance: We have to wear identity cards at college.
• Need not expresses the absence of necessity: You need not bring your own chair.
• The negative form must not expresses prohibition: You must not enter this room.
• Have to changes according to tense and subject: She has to work, They had to work, and He will have to work.
• Must generally does not have ordinary past or future forms, so had to and will have to are used when necessary.

The distinction between must not and need not is especially important: the first prohibits an action, while the second permits the action but says it is unnecessary.

Should and ought to are modal expressions used to give advice, express duty, and indicate expectation.

• Advice: You should read the instructions carefully.
• Moral duty: We ought to help people in difficulty.
• Expected result: The train should arrive soon.
• Likely situation: The students ought to be in the library by now.
• Regret or criticism in the past: You should have informed the teacher earlier.

The main difference is grammatical:

• Should is followed directly by the base verb: You should study.
• Ought to is followed by to and the base verb: You ought to study.

Both forms generally express similar meanings, although ought to can sound more formal. The negative forms are should not and ought not to.

Will, would, and shall express future meaning, willingness, requests, habits, offers, and suggestions.

• Will expresses future intention or prediction: I will meet you tomorrow.
• Will expresses willingness: She will help us with the project.
• Would expresses a polite request: Would you open the window?
• Would describes a repeated past habit: During the holidays, we would visit our grandparents.
• Would occurs in conditional sentences: I would travel more if I had enough time.
• Shall may be used with I or we to make suggestions: Shall we begin the discussion?
• Shall may express a formal promise or requirement: The applicant shall provide valid documents.

In modern general English, will is more common than shall for ordinary future statements.

A modal verb normally controls the form of the verb that follows it. The main rules are:

• A modal is followed by the base form of the verb: He can write.
• The word to is not used after ordinary modals: They must leave, not They must to leave.
• A modal does not take an infinitive ending, a participle ending, or a third-person singular ending: She may come, not She mays comes.
• A modal can be followed by be: The answer may be correct.
• A modal can be followed by be + present participle for a continuous meaning: He may be waiting outside.
• A modal can be followed by have + past participle for a perfect meaning: They might have forgotten the appointment.
• A modal can be followed by be + past participle for a passive meaning: The form must be submitted today.

Negative sentences with modal verbs are formed by placing not immediately after the modal.

Structure:

Subject + modal + not + base verb

Examples:

• You cannot enter this room.
• She should not waste her time.
• They may not attend the meeting.
• We must not disturb the speaker.

Important points include:

• Cannot is usually written as one word, although can not may occur in special contexts.
• Common contracted forms include can't, couldn't, shouldn't, wouldn't, won't, and mustn't.
• Must not expresses prohibition.
• Need not expresses lack of necessity.
• May not can mean either that something is not permitted or that it is possibly not true, depending on context: You may not leave means no permission, while He may not come expresses possibility.

The modal remains unchanged regardless of the subject.

Questions with modal verbs are generally formed by placing the modal before the subject.

Structure:

Modal + subject + base verb + complement?

Examples:

• Can you solve this problem?
• May I use your dictionary?
• Should we inform the principal?
• Will they join the programme?

The following rules apply:

• The modal is placed at the beginning of a yes-or-no question.
• The main verb remains in its base form.
• Do, does, and did are not used with a modal for question formation.
• Question words are placed before the modal when needed: Why should we wait?
• A modal question may express a request, offer, suggestion, permission, prediction, or obligation.

For example, Could you lend me your notes? is a polite request, while Should I submit the report today? asks for advice or instruction.

Modal verbs express ability mainly through can, could, and related expressions.

• Present ability is expressed with can: Maya can communicate clearly.
• Present inability is expressed with cannot or can't: Maya cannot attend the workshop today.
• General past ability is expressed with could: He could read fluently at the age of six.
• Past inability is expressed with could not or couldn't: She could not understand the lecture.
• Ability in a specific past situation is often expressed with was able to or managed to, especially when the action was successfully completed: He was able to solve the difficult question.
• Future ability is commonly expressed with will be able to: After the training, they will be able to use the software.

The modal must be followed by the base form when it is used directly, as in can speak and could write.

Modal verbs show how certain or uncertain a speaker feels about an event.

• Must expresses a strong logical conclusion: The door is locked, so the office must be empty.
• May expresses a reasonable possibility: The manager may arrive later.
• Might and could express weaker or more uncertain possibilities: The manager might arrive later or The manager could arrive later.
• Cannot expresses strong logical impossibility: That cannot be the correct answer.
• Should expresses an expected or likely result: The parcel should arrive tomorrow.

The degree of certainty depends on the modal and the context. The speaker's choice of modal therefore communicates attitude, not just the time of an action. These verbs are followed by the base verb in simple structures, as in may come, must be, and could happen.

Modal verbs perform important functions in rules, instructions, and formal communication.

• Permission: can, could, and may can be used to ask for permission. Can I leave early? is informal, while May I leave early? is more formal.
• Giving permission: can or may can be used: You may use the laboratory.
• Prohibition: must not or cannot expresses that an action is forbidden: Visitors must not touch the equipment.
• Obligation: must, should, and have to express different levels of duty. You must wear a helmet expresses a strong requirement, while You should wear a helmet generally gives advice.
• Lack of obligation: need not and do not have to show that an action is optional: You do not have to submit the form today.

The meaning of each modal should be interpreted in relation to the situation and level of formality.

Modal verbs are frequently used in the main clause of conditional sentences to express possibility, advice, ability, or consequence.

Examples include:

• Possibility: If the weather improves, we may go outside.
• Ability or opportunity: If you practise regularly, you can improve your pronunciation.
• Advice: If you feel unwell, you should consult a doctor.
• Hypothetical result: If I had more time, I would learn another language.
• Past possibility or regret: If they had left earlier, they could have caught the train.

The conditional clause normally contains a suitable tense, while the main clause contains a modal construction. The modal is followed by the base verb, except in perfect structures such as could have completed or would have attended. Modal choice changes the meaning of the result clause.

A modal verb followed by have + past participle refers to a past action or situation. This structure is called the modal perfect.

Structure:

Subject + modal + have + past participle

Uses and examples:

• Past possibility: She may have forgotten the meeting.
• Past uncertain possibility: They might have taken the wrong road.
• Past ability or opportunity: He could have won the competition.
• Past criticism or advice: You should have checked the details.
• Past obligation that was expected: The students ought to have completed the work.
• Strong conclusion about the past: The visitor must have left already.
• Negative conclusion: He cannot have understood the instructions.

The past participle must be used after have, and the modal itself remains unchanged.

Modal verbs can be used in passive sentences when the focus is on the action or receiver rather than the person performing it.

Structure:

Subject + modal + be + past participle

Examples:

• The assignment must be submitted by Monday.
• The rules should be followed by everyone.
• The documents may be checked at the entrance.
• The equipment cannot be used without permission.

For a past passive meaning, use:

Subject + modal + have been + past participle

For example, The report should have been completed yesterday.

The modal is followed by be, not is, are, or was, because a modal must be followed by the base form. The past participle carries the passive meaning.

A modal can be followed by be + present participle to show that an action is in progress or temporary.

Structure:

Subject + modal + be + verb-ing

Examples:

• She may be preparing for the examination.
• They could be waiting outside.
• He must be working on the assignment.
• You should be listening carefully.

This construction can express:

• A possible action in progress: The teacher may be explaining the topic.
• A logical conclusion about a current action: The students must be revising.
• Advice about an activity that should currently be happening: You should be taking notes.

The verb be remains in its base form after the modal, and the main verb takes the -ing form.

Used to, would, and the ordinary past tense can all refer to past actions, but they do not have exactly the same use.

• Used to describes a past habit or state that is no longer true: I used to live in Delhi.
• Would describes repeated past actions, especially in narrative contexts: Every summer, we would visit our relatives.
• Would is generally not used for past states. We say I used to know him, not usually I would know him.
• The ordinary past tense can describe a completed event or a past habit when the context is clear: We visited the museum every month.
• Used to has a negative form, did not use to, and a question form, Did you use to...?
• Would also has other meanings, including politeness and conditionality: Would you help me? and I would help if I could.

Therefore, the surrounding context determines the appropriate form.

Modal verbs follow special rules regarding subject agreement and tense.

• A modal has the same form with every subject: I can, she can, and they can.
• Modals do not take -s in the third-person singular: He must leave, not He musts leave.
• Most modals do not have ordinary tense forms. Their meaning and context often indicate time.
• Could, might, should, and would may refer to past time or express special meanings, but they are not always simple past forms of can, may, shall, and will.
• For future ability, use will be able to, not will can.
• For past necessity, use had to, not musted.
• For future necessity, use will have to, not will must.
• After a modal, the next verb remains in the base form: She will have to attend and He may be able to help.

These rules prevent incorrect forms such as cans, musted, and will can.