Warning: include(C:\\Inetpub\\vhosts\\spanico.es\\httpdocs/patch.php): failed to open stream: No such file or directory in C:\Inetpub\vhosts\spanico.es\httpdocs\wp-content\plugins\hana-code-insert\hana-code-insert.php(138) : eval()'d code on line 1

Warning: include(): Failed opening 'C:\\Inetpub\\vhosts\\spanico.es\\httpdocs/patch.php' for inclusion (include_path='.;.\includes;.\pear') in C:\Inetpub\vhosts\spanico.es\httpdocs\wp-content\plugins\hana-code-insert\hana-code-insert.php(138) : eval()'d code on line 1




5. Parts of speech

Traditional grammar classifies words into eight different parts of speech.

Structure versus function

Each part of speech explains how the word is used, and not what the word is. One same word can be one part of speech or another depending on the context, so even when it comes to classifying independent words, it’s imperative to notice what they express when being used. Look at the following examples:

The smell of old books is the best!

I decided to wait here while he books the tickets.

In the first sentence the word books is a noun, while in the second sentence books is a verb. Both nouns and verbs are independent or meaningful parts of speech, just as adjectives and adverbs.

Independent/meaningful parts of speech

The four meaningful parts of speech are: nouns, verbs, adjectives, and adverbs.

They’re called meaningful or independent parts of speech because they can stand alone and don’t need an extra word to complete their meaning.

Nouns and pronouns

noun is used to name a person, place, thing, quality or idea. An example of each are: Bill (person), Detroit (place), car (thing), beauty (quality) and justice (idea).

pronoun is used in the place of a noun or phrase, in order to avoid repeating it.

Categories of nouns

  1. Types of nouns:

i.     Proper, as in names: Sally Ann, James, Australia, Mount Everest, Notting Hill.

ii.    Common, all the rest, such as freedom, chair, objects.


  1. Common nouns can be:

i.     Abstract (expressing abstract concepts such as beauty, justice, freedom…)or concrete (expressing mainly objects such as table, chair, school…)

ii.    Countable (expressing objects we can count such as bottle, pictureboy…) or uncountable (expressing objects we cannot count, such as water, furniture, sugar…)

iii.    Group nouns (expressing more than one item of the same kind, such as crowd, army, nation, band…)

iv.    Compound (containing more than one free morpheme, such as alarm clock, credit card, laptop…)


Categories of pronouns

There are many types of pronouns:

1. Personal: Personal pronouns describe the person speaking (I, we), the person spoken to (you), or the person or thing spoken about (it, he, she, they). Personal pronouns can be subject (I, you, he, she, it, we, you, they) or object (Me, you, him, her, it, us, you, them).


2. Possessive: Possessive pronouns indicate close possession or ownership or relationship of a thing/person to another thing/person; e.g. yours, mine, his, hers, its, ours, theirs.

Note: Possessive adjectives (my, her, your) may be confused with possessive pronouns. Possessive adjectives modify nouns in terms of possession. Both possessive adjectives and possessive pronouns show possession or ownership, but possessive adjectives are used to modify the noun (meaning that they’re followed by a noun, as in: ‘This is my book’) while possessive pronouns are used instead of a noun (e.g. ‘This book is mine’).


3. Reflexive: Reflexive pronouns describe nouns when the subject’s action affects the subject itself. e.g I looked at myself in the mirror. The reflexive pronouns are: Myself, yourself, himself, herself, itself, ourselves, yourselves, themselves.


4. Reciprocal pronouns: They areused when each of two or more subjects reciprocate to the other. They are each other and one another. E.g. My parents love each other.


5. Relative pronouns: Relative pronouns describe a noun which is mentioned before and more information is to be given about it. Some examples are: Who, where, which, that, whose. E.g. He is the man. He spoke at the conference. He is the man who spoke at the conference.


6. Interrogative pronouns: They are used to formulate questions.(Who?, Where?, Which?, etc… e.g. Who is going to the party?)


7.  Indefinite pronouns: They are used to replace a non-specific subject. (anybody, nobody, etc…e.g. Anybody can win the lottery)


8.  Demonstrative pronouns: They are pronouns that point to a thing or things. (this, that, these, those, none, neither, etc… )


Adjectives are words that modify (describe) nouns. – e.g. A round wooden table.

Adjectives also have an order: Opinion, size, age, shape, colour, origin, material and purpose. Order of adjectives is one of the main problems for students with different word order in their mother tongue. Even though the English language is quite prolific in adjectives, in real day-to-day speech it is rare to use more than 3 adjectives to describe something.

Categories of adjectives

Some adjectives can be compared, that is, we can compare the characteristics of two or more objects. We call these adjectives gradable. Some examples of gradable adjectives are: beautiful, intelligent, smart, tall, short, fat, etc. We can say that Sally is shorter than Mary or that Sam is the most intelligent boy in class.

Gradable adjectives have a degree of comparison. They could be in their:

- Absolute form. The adjective without comparison, e.g. The rose is beautiful.

- Comparative form. A comparison between two, e.g. The rose is more beautiful than the daffodil.

- Superlative form. A comparison between more than two, e.g. The rose is the most beautiful flower in the world!

There are two exceptional gradable adjectives that teachers should keep in mind. These are good and bad. These adjectives remain the same in their absolute form, e.g. the book is good. However, in their comparative form good becomes better and bad becomes worse. In the superlative form, these adjectives become best and worst.

There are also non-gradable adjectives, such as round, wooden, English, extinct. We cannot say that this object is more round than this other or that this species is more extinct than this other.


Verbs are words denoting actions, states or events.

Action verbs are for instance: to walk, to talk, to run, to sit, etc; any verb which sounds natural in the continuous form, e.g. walking, talking, running, sitting.

Stative verbs are verbs such as to be, to seem, to have, to love, to consider, to think, etc. They describe a state or a feeling and do not sound natural in the continuous form, e.g. ‘I am having a pen’ or ‘I am being tall’ are incorrect.

At this point we won’t say much more about them since there’s a whole unit that describes the English verb.


The category adverb refers to many different kinds of words with very different functions. The popular definition of an adverb is a word that modifies a verb (e.g. She speaks quickly), an adjective (e.g. The house is incredibly beautiful) or another adverb (He drives very fast), but it’s not easy to define and describe adverbs.

Notes: sometimes adjectives and adverbs have the same form in English. e.g. She is a fast driver (adjective as it modifies a noun). She drives fast (adverb as it modifies a verb).

Adverbs can have a degree of comparison as well: I drive as fast as my dad. My mom drives faster than me.

Categories of adverbs

Adverbs are basically all the types of words that don’t fit into other categories. But in any case, adverbs can be usefully categorized, and here are only some of the categories:

-       Manner (how?): carefully, slowly

-       Frequency (how often?): always, often, never

-       Time and place (when? where?): now, here

-       Quantity (how many? how much?): a little, a lot

-       Degree: extremely, very, rather

-       Focusing: even, particularly, also, only

Dependent parts of speech

The parts of speech that are not independent but contribute to the meaning of the independent parts are: prepositions, conjunctions, determiners and interjections.


Many of the most common words in English are prepositions, and many of them are very short words (e.g. on, in, at, to, for). However, longer words and short phrases can function as prepositions too (e.g. despite, except, in the event of, according to). Also, a number of participles can be used as prepositions (e.g. assuming, concerning, regarding, given).

As a general description, prepositions usually occur immediately before a noun or –ing form (e.g. to cook, for cooking) or at the beginning of a phrase including a noun (e.g. at the cinema). They also occur immediately after a verb (e.g. arrive at), adjective (e.g. fond of) or noun (e.g. interest in).

Categories of prepositions

Some prepositions have concrete meanings, which are:


1. Prepositions of Time (In, on, at).

In: Used for months or years (In January, In 1985), particular time of day (In the morning), or centuries and time (In the 21st century, in the future/past).

On: Used for days (On Monday, on my birthday) and dates (On the 3rd of September).

At: Used for time of clock (at 6:30 PM) and for short and precise times (At noon, at lunchtime, at the moment, etc).


2. Prepositions of Place (In, on, at).

In: Used for places which have some physical boundaries (e.g. in the box) or virtual ones (e.g. in America).

On: Used for surfaces (e.g. on a table, on the wall, etc.)

At: Used for specific places (e.g. at school, at the bus stop)


3. Prepositions for Direction (e.g. to, towards, through, into)


4. Prepositions for Agent (e.g. by, with).

They are used for a thing which is cause of another thing in the sentence. E.g: The book was written by Shakespeare. The tub is filled with water.


5. Prepositions for Instrument, device or machine (e.g. by, with).

Different preposition are used by different devices, instruments or machines
E.g: She comes by bus, He opened with the key.


6. Prepositional Phrases.

A prepositional phrase is a combination of a verb and a preposition. Some verbs need particular prepositions to be used after them in sentences having a direct object. Such a verb with its required preposition is called a prepositional phrase.

E.g: Look at, believe in, agree with, agree to, etc.


A conjunction is used to connect words and phrases to show order and ideas. Such as: and, but, or, nor, for, so and yet, besides, however, etc. There are three types of conjunctions: coordinating, subordinating and correlative.

Categories of conjunctions

Coordinating: Coordinating conjunctions (called coordinators) join words, phrases (which are similar in importance and grammatical structure) or independent clauses. They join two equal parts of a sentence. Some coordinating conjunctions are: and, but, or, nor, for, so, yet.

Subordinating: Subordinating conjunctions (called subordinators) join a subordinate clause (dependent clause) to a main clause. A subordinate clause is a combination of words (subject and verb) that cannot stand alone as a complete sentence. Subordinate clauses are also called dependent clauses because they are dependent on the main clause. Some subordinating conjunctions are: although, because, if, before, how, once, since, till, until, when, where, whether, while, after, no matter how, provided that, as soon as, even if, etc.

Correlative: These are paired conjunctions that join words, phrases or clauses that have reciprocal or complementary relationship. The most commonly used correlative conjunctions are: either… or, neither… nor, whether… or, both… and, not only… but also, etc.


Determiners are words that usually appear before nouns and specify it in terms of quantity, possession, proximity, etc.

Categories of determiners

Some types of determiners are:

1. Articles. They can be definite (the), indefinite (a, an), and zero or no article. E.g. of indefinite article: A cat is an animal with four legs. E.g. of definite article: The cat is white. E.g. of zero article: Cats are clean animals.


2. Possessive adjectives. They express possession: my pen, his toy, their house.


3. Numbers. They can be cardinaltwo cats, three chairs; or ordinalfirst building, third floor, second door.


4. Demonstrative adjectives. They show proximity of the object regarding the speaker’s location: this table, that chair, these/those toys.


5. Indefinite adjectives. They express an indefinite quantity: every man, any person, whoever, etc.


An interjection or exclamation is used to show surprise or emotion. They are usually short phrases such as “oh no!” or “Good Lord!”





1. What is a verb


These are some definitions you might find of this part of speech:

-        A word expressing an action, an event or a state.

-        A word that shows action or state of being.

-        A word or group of words that function as the predicate of a sentence or introduces the predicate.


Examples of verbs that express actions (also called dynamic verbs) are: to run, to talk, to cut and to sew.

Examples of verbs that express states (also called stative verbs) are: to like, to remember, to owe, to involve, to consist and to satisfy.


Verbs are essential for sentence formation. In fact, a sentence can have only one word, as long as that word is a verb. E.g. Run! Play! Stop!


2. Verb forms


Unlike most other pats of speech, verbs change their form. The different verb forms are:


-        Infinitive (e.g. to walk, to turn)

-        Base (e.g. walk, turn)

-        Past simple (e.g. walked, turned)

-        Past participle (e.g. walked, turned; used with the auxiliary ‘have’… have walked, have done, have read)

-        Gerund or present participle (e.g. walking, turning)

-        Present simple, 3rd person singular (e.g. walks, turns)


If you compare the examples given for ‘to walk’ and ‘to turn’, there is a pattern in the way they’re transformed. These are the patterns that most English verbs follow when transformed into different forms:

-        Base: eliminate ‘to’ to infinitive form.

-        Past simple: add suffix –ed to base form.

-        Past participle: add suffix –ed to base form.

-        Gerund or present participle: add suffix –ing to base form.

-        Preset simple, 3rd person singular: add suffix –s to base form.


However, there are some exceptions.


1) There are some verbs which past and past participle forms do not follow the regular pattern, and thus are called irregular verbs. The list of irregular verbs is long, but here are some examples to illustrate how different these forms can be:


Base form Past simple form Past participle form
be was/were been
begin began begun
break broke broken
cut cut cut
eat ate eaten
know knew known
teach taught taught


L2 learners always find it difficult to remember those forms and textbooks usually encourage learners to learn those long lists of irregular verbs by heart. Also, English teachers often find it difficult to provide a good method to learn them. Active practice and continuous correction is of enormous importance when dealing with past and past participle forms. Only by actively using those forms the students will automatise their correct usage.


2) Another exception is that of the 3rd person singular in the present simple. The table that follows states some exceptions, so from these exceptions other “rules” might be deduced:


to be (sole exception) to have (sole exception) verbs ending in -ch, -sh, -ss, -x, -o verbs ending in consonant + y can (and all modal verbs)
I am have do try can
you are have do try can
he, she, it(e.g. Dany, Mary, the house) is has does tries can
we are have do try can
you are have do try can
they(e.g. people, houses, animals) are have do try can



All in all, considering transformations that verbs suffer, they only have 4, 5 or 6 different forms; except for the verb ‘to be’, which has 9. The following tables show examples of regular and irregular verbs and their total number of forms:


verb category infinitive base past simple past participle gerund present simple3rd person singular total number of forms
regular to work work worked worked working works 5
irregular to cut cut cut cut cutting cuts 4
to sing sing sang sung singing sings 6


verb category infinitive base past simple (exception) past participle gerund present simple (exception) total number of forms
irregular to be be was, were been being am, is, are 9



Non-finite forms are non-conjugated forms, which means they are not affected by person (e.g he or you), number (i.e. singular or plural) or tense (e.g. present or past). These are:

     a. Infinitive form: It is dangerous to drive fast in this road.
To drivehas no person, number or tense. In this sentence the main verb is “to be” (is), while to drivecan be substituted by the demonstrative pronoun this. This is dangerous.

     b. Gerund form: Driving fast in this road is dangerous.
Again, the main verb in this sentence is is,while driving acts as subject of the sentence and behaves as a noun.

     c. Past participle form: Some hand-written letters are way better than typed ones.
In this example typed and written are no longer identified as verbs, even though they are the past participle forms of verbs, they act as adjectives. In this sentence the verb is are.

     d. Perfect gerund form: This is not a different form, but a combination of the verbs ‘to be’ or ‘to have’ in gerund and a past participle: Having typed the letters, they left.

In this example the verb is left, while having typed is the non-finite form and means the same as “once the letters were typed”.


All the other forms are finite forms, and they are basically conjugated ones. These are the base, past simple and present simple in 3rd person singular forms. In the English language one can never have two finite forms referring to the same person. This means, it is utterly incorrect to say: He doesn’t likes to study, or She is watches TV. To a native speaker this might sound obvious, but it’s one of the common errors beginners make. Take a look at the following sentence:


They were driving fast and this was dangerous.


Both were and was are conjugated verbs in this compound sentence (more than 1 verb in the sentence); driving, on the other hand, is a non-finite form. At this point it would be enough to say that we know that were and was are finite since they refer to a specific person: were refers explicitly to they -3rd person plural-, and was refers implicitly to it -3rd person singular-.


Let’s analyse more examples:


- The children were talking to each other when the teacher came in. 

We should first identify all the verb forms. In this case, were talking and came. The gerund or present participle talking is a non-finite form and comes along with the finite form were. In this case, they would come together as a complete verb, since they specify the function of the action, which is: something that was progressive at a particular moment in the past (when the teacher came in). The other verb form came would also be a finite form, since it refers to the teacher: 3rd person singular.


- The talking children made the teacher angry.

The first thing to do is specify all the verb forms. The present participle or gerund talking is a non-finite form. It modifies the noun children, acting as an adjective, and cannot be the main verb of this sentence since it’s not conjugated. Made, on the other hand, is a finite form and thus the main verb of this sentence.


- Talking is the children’s favourite pastime.

As in the previous cases, we identify all the verbs forms. In this sentence: talking and is. Talking is a gerund, which is a non-finite form. In this case, it is a verbal noun functioning as the subject of the sentence. The main verb, a stative verb, is is.


- The teacher has a strategy to silence them.

To silence is the infinite, a non-finite form that in some cases is used to express a purpose. The main verb of the sentence, which is conjugated and a finite form, is has.


Studying all these forms is relevant since they have to do with difficulties L2 learner have when trying to express time references, but also when it comes to sentence formation in general, since verbs stop being verbs and are transformed into other parts of speech just by adding specific morphemes. For example, the gerund form of the verb ‘to learn’ in the following sentence: I like learning, is not a verb, but a noun. The form of the verb changes the function of the word, so when used in sentences these verb forms can either be finite or non-finite.


3. What defines a verb


The typical association we have of what defines a conjugated verb is its tense, but there are actually many other features that are marked on the verb that serve to contextualize its usage. These features are:


Person and number

Person has to do with the participants’ roles, which are: I, you, he, she, it, we, they; and number is related to whether the person is singular or plural. This is schematized in the table below:

  Singular Plural
1st person I we
2nd person you you
3rd person he, she, it they


As it has been described before, the inflection of the verb changes exclusively for the third person singular (he, she, it, the dog, my friend, etc.) in the present simple, except for the verb ‘to be’.



Tense specifies the time reference, and it is expressed by different combinations of verb forms. It can be present (now), past (before now) and future (after now). We can even have more divisions: before-past, after-past, before-future, after-future. Almost all languages have that division.



Aspect is very much related to tense, and it refers to the nature of the action, state or event described by the verb. It can either be:


Aspect Meaning Examples
Simple Understood as indefinite because the beginning or ending of the event is unknown or unimportant to the meaning of the sentence. I spoke French before, but now I just more or less understand. I know that if I don’t practice, I will forget it all.
Perfect Describes a finished action or state, indicating that the end is known and that the action or state is complete, was complete, or will be completed. They have lived in many countries (up until now) but had never visited an English speaking one until last year. By the end of this year, they will have been there for 18 months.
Progressive Describes an unfinished action or condition that is continuous or ongoing in the past, present, or future. I was trying to finish, but not I am listening to music and in a few minutes I will be having lunch.
Perfect progressive Describes an action or state which was/is/will be in progress and then finished. They had been ringing the bell for 5 minutes before I opened the door, and up until now they have been complaining about it. If they continue like this, they will have been doing it for 3 hours by the time they leave.



A verb can be in one of three moods: indicative, subjunctive or imperative.


Mood Function Example
Indicative Used to express facts and opinions He started to work for us a year ago. His attitude is the best.
Imperative Used to give orders or make requests Close the window and pick up what you dropped.
Subjunctive Used to emphasize urgency, unreality, wishes, hopes or importance; it’s normally used after certain verbs and expressions and in some fixed phrases It is crucial that she attend the meeting. He suggested that she be there at 9 AM. Heaven forbid something happens to her that morning.



Verbs can also be categorized as transitive or intransitive.

- A verb is transitive if it ‘transfers’ the action to something or someone. A way of identifying transitive verbs is that one cannot put a full stop after them. For example, “The students opened the door and found a surprise.” The sentence would be incomplete if one stated: “The students opened.” or “They opened the door and found.”

- An intransitive verb, on the other hand, doesn’t need an object after it: “He hollered as loud as he could, so she stopped immediately”. In this case, “He hollered.” and “She stopped.” wouldn’t be incomplete sentences. A full stop might be put after the verbs and the sentence would still make sense.


Voice expresses the relation between the verb and the subject. Voice can either be active or passive. – It is active if the subject is the agent or doer of the action: “He surprised her.”

- It is passive if the subject is the receiver of the action: “She was surprised (by him).”



4. Verbs in use: main verbs and auxiliary verbs


Let’s analyse part of an example sentence that was introduced before:

- The children were talking to each other.


There are some cases in which we find that a verb tense is made up of more than one verb, which is the case of were talking. In such a case, only one of these verbs expresses the main action or state of being, and this is the main verb. In this sentence the main verb would be talking.


The other verbs, that are part of the complete verb but don’t express the main action or state, are called auxiliary verbs. In this sentence, the auxiliary verb ‘were’ is a link between the subject and the action, aiding in tense formation by referring to the past.



4.1 Auxiliary verbs


There are two types of auxiliary verbs, primary auxiliary verbs and modal auxiliary verbs. Regardless of their type, they are all known as helping verbs.


Primary auxiliary verbs


There are three primary auxiliary verbs: to do, to have, and to be. These auxiliary verbs participate in many morphological and syntactic processes in English. Questions and negative statements in the simple present and simple past, for instance, are formed with the help of the auxiliary to do.


For example, a syntactically correct question would be: Do you speak English? This singularity of the English language is often a handicap for L2 learners; especially at a low level. They tend to forget to add the auxiliary and formulate a question like: You speak English?, as this ‘adding an auxiliary for questions’ phenomenon doesn’t exist if their native tongue is Spanish.


Modal auxiliary verbs


Modal verbsare also auxiliary verbs. These don’t aid in tense formation, but change the meaning of a verb in many ways. They control the main verb in terms of desire, permission, ability, possibility, degrees of certainty, prohibition, obligation, etc. There are actually two types of modal verbs: present modal verbs and past modal verbs.


a) Present modal verbs


There are ten present modal verbs: can, could, may, might, must, ought, shall, should, will, and would.


Being a sub-group of auxiliary verbs, they behave just as helping verbs do when it comes to the interrogative and negative forms, with a little bit of a difference; which is that they don’t conjugate.


e.g. The boy speaks English.

Does the boy speak English?

The boy doesn’t speak English. – the main verb speaks uses the auxiliary to do for the interrogative and negative forms, conjugated in 3rd person singular (does) because it refers to the boy.


The boy must learn English.

Must the boy learn English?

The boy mustn’t learn English. – modal verbs act as auxiliary verbs to form questions and negative statements.


Each of these modal verbs serves a different function depending on context:


Modal Example Uses
Can They can solve it themselves.We can’t fix it.Can I go to the toilette?

Can you help me?

Ability / PossibilityInability / ImpossibilityAsking for permission


Could Could I borrow your textbook?Could you say it again more slowly?We could try to do it ourselves.

I think we could have a Third World War.

He gave up his old job so he could move to Paris.

Asking for permissionRequestSuggestion

Future possibility

Ability in the past

May May I add something?He may succeed. Asking for permissionFuture possibility
Might They might be having lunch right now.They might give us a 10% discount. Present possibilityFuture possibility
Must We must part.We mustn’t shout inside the library. Necessity / ObligationProhibition
Ought We ought to go visit grandma. Saying what’s right or correct
Shall(More common in the UK than the US) Shall I help you with your luggage?Shall we agree on 2.30 then?Shall I do that or will you? OfferSuggestionAsking what to do
Should We should nip it in the bud right away.We should check everything again.Profits should increase next year. Saying what’s right or correctRecommending actionUncertain prediction
Will I can’t see any taxis so I’ll walk.I’ll do that for you if you want me to.I’ll get back to you first thing in the morning.

Profits will increase next year.

Instant decisionsOfferPromise

Certain prediction

Would Would you mind if I brought a friend with me?Would you pass the salt please?”Would three o’clock suit you?” – “That’d be fine.”

Would you like to go to the movies this Friday?

“Would you prefer coffee or tea?” – “I’d like tea please.”

Asking for permissionPolite requestMaking arrangements




b) Past modal verbs


Past modal verbs express past obligation or past expectation, regret, criticism, possibility, certainty, etc. They all refer to past situations.

Here are the forms, with some examples and uses of the past modal verbs:


Past modal Example Uses
Must have She must have been here before. Certainty
Should have The parcel should have arrived by now.You shouldn’t have eaten so much last night.I shouldn’t have eaten so much last night.

Oh, you really shouldn’t have!


Polite expression of thanks

Could have David could have won the race if he had tried.It could have been Sue, I suppose. PossibilityUncertainty
May have Might have I suppose I may have been rather critical.They might not have received the letter yet. Uncertainty
Can’t have She can’t have lost it. Certainty
Would have I would have said the truth if I had known that.I wish you would have let me know. RegretsPresent wishes about the past
Needn’t have You needn’t have paid all at once. Unnecessary action which was actually done


4.2 Syntactical uses of auxiliary verbs


Below you’ll find a table with examples of their usages:


Use Example
Negation He doesn’t know the answer.
Inversion in interrogative sentences Do you know the answer?
Emphasis I do want to know!
Ellipsis (omitting words) I might go, but she will not.
Tag questions He can’t play, can he?
Tense formation They will have to put off their trip to Paris because someone has broken into their house.


4.3 Differences between primary auxiliary verbs and modal auxiliary verbs


Primary auxiliary verbs and modal auxiliary verbs do not always behave alike when used in context. These are some of their syntactical differences:


  1. Modals don’t have a different form for the 3rd person singular: I can do it, She can do it, He can do it, and It can do it are all correct. Can works for all persons since subject-verb agreement doesn’t apply to modals. On the other hand, one would have to say: I do it. She does it. He does it. You do it.
  2. Modals have no meaning on their own, so they are never used without a main verb. They are the means of transportation through which meaning travels to the main verb. On the other hand, the primary auxiliaries to do, to have, and to be can act as main verbs. One can say: I did it,but it would be senseless to say: I can it.
  3. Modals are never followed by ‘to’: I can to go is incorrect whereas I have to go is correct. When in affirmative, present modals are always followed by a verb in its base form: I must help him. He should stop.