What does the phrase i can find mean? Modal verb Can. Examples of using the modal verb can

The modal verb can appears already on the first pages of elementary-level textbooks. Everyone knows that it means “I can, I can.” But not everyone knows that the functions of the verb can are not limited to this. In this article, we will go into detail about the uses and functions of the verb can and its past tense form (could).

Let's start with grammatical characteristics.

  • The verbs can and could do not have third person endings. singular: he can, she can.
  • The verbs can and could do not need auxiliary verbs to form negative and interrogative forms: Can you...? Could he...?
  • Negative form of the verb can: cannot. Full form usually written in one word, together.
  • Shortened negative form: can"t. In British English it is pronounced , in American English - [ kæ nt].
  • Negative form of the verb could: couldn'tt, pronounced ["kudnt].
  • The verbs can and could do not have infinitive or participle forms. If there is a need to use these forms, use the equivalents of these modal verbs: be able, be allowed.
  • Used after the verbs can and could semantic verb without the particle to.

Now let's talk about the meanings of the verb can (could).

Could is usually taken as the past tense form of the verb can:

He can ride a bike now, but he couldn’t ride two years ago. - He knows how to ride a bike, but two years ago he couldn’t.

I couldn't dance well, but after a few lessons I can dance better. - I couldn't dance well, but after a few lessons I can dance better.

In this article we look at the verbs can and could (as a form of can), and their general values, but it would be a mistake to assume that these verbs always mean the same thing.

Modal verb could acts as an independent modal verb, which has its own functions that deserve a separate article.

The main functions of the verb can (could):

Let's look at all these meanings.

1. Ability, skill (Can, could)

We can use the modal verb can when we talk about abilities related to knowledge, skills, strength, nature, and so on:

We can speak English very well. - We can speak English well.

Only Mike can open this door. - Only Mike knows how to open this door.

Cats can catch mice. - Cats can catch mice.

She can play the piano a bit. - She knows how to play the piano a little.

My bike can accelerate to 150 kph. - My motorcycle can accelerate to 150 km/h.

In addition, can is used to describe typical characteristics of something or someone:

This dog can bite. Don't come close to it. - It's the dog that bites. Don't come close to her.

My boss can be really furious. - My boss may lose his temper.

Summers can be very hot in our country. - In our country it can be very hot in the summer.

Can (could) is always used when talking about the ability to speak a language or mastery of musical instruments:

Can you speak Russian? - Do you speak Russian?

She can play the guitar. - She plays the guitar.

Can is used when talking about what is possible/impossible under certain circumstances:

I can't play the guitar. It's out of tune. - I can't play the guitar. She's upset.

They can go for a picnic because the weather is fine. - They can go on a picnic because the weather is good.

We can go to the cinema or we can go to the theatre. - We can go to the cinema or we can go to the theater.

Abilities and opportunities in the past are indicated by the modal verb could:

I could write when I was five. - I could write when I was five years old.

My mother could skate very well. - My mother knew how to skate very well.

We could play football for hours when we were children. - We could play football for hours when we were children.

2. Permission

In order to ask for permission, give permission or refuse permission, the verb can is used:

Can I ask you a question? - Can I ask you a question?

You can go out when you do your homework. - You can go for a walk when you finish your homework.

You can"t leave the room until the end of the exam. - You cannot leave the room until the exam is over.

When permission is denied, “mitigating” phrases are usually used:

I"m afraid you can"t enter this room. - I'm afraid you cannot enter this room.

Sorry, but you can't open the book. - I'm sorry, but you can't open the book.

Could can also be used to ask for permission. The question with could is more polite and formal than with can. However, could is not used to give or deny permission; can is used for that:

Could I read this letter? - Yes, of course you can. - Can I read this letter? - Sure you can.

Could I look at the documents? - No, I "m afraid you can"t. - Can I look at the documents? - I'm afraid not.

Can and could are also used when discussing any laws or established rules:

Only employees of our company can use the photocopier. - Only employees of our company can use the photocopier.

Can the pupils bring mobile phones to the lesson? - Students can bring Cell phones to class?

3. Requests

Can and could in questions like - Can/could you...?- can express a request. The difference between them is that could- a more formal form, more polite and less specific. If we compare their translations, then Can you...? will sound like "Can...?" or "Can you...?", A Could you...? : "Could you...?":

Can you help me translate this text? - Can you help me translate the text?

Could you tell me the way to the libtary? - Could you tell me how to get to the library?

4. Offers and suggestions

There are two types of offers: when you offer to do something for someone (this is a request) and when you offer to do something together (this is a suggestion).

If you want to offer to do something for someone (request), use I can or Can I...? . Question Can I...? has the same meaning as "Would you like me to...?" (Do you want me...?/Do you want me...?):

I can fix your car if you like. - I can fix your car if you want.

Can I wash the dishes? - Should I wash the dishes?

If your sentence is more of a hint and is vague, then use I could:

I could give you a few recommendations if you would like. - I could give you some recommendations if you want.

We could help you with transportation if you still need help. - We could help you with transportation if you still need help.

To suggest doing something together (suggestion), use We can/ we could, following the same rule: could- more formal and vague:

We can go to the gallery on Sunday. - We can go to the gallery on Sunday.

We could go to the gallery on Sunday. - We could go to the gallery on Sunday.

5. Can with verbs of perception

As you know, verbs of perception such as see, hear, taste, smell, feel. Therefore, to convey that the action is happening at the moment of speech, the modal verb can is used:

I can see you very well. - I see you very well.

I can"t hear you. I"ll call you later. - I can not hear you. I'll call you later.

6. Speculation

The verb can can be found in set expressions:

Can't help- to be unable to hold back

I can't help laughing when I watch this movie. - I can't help laughing when I watch this movie.

Can't stand- can't stand it

I can't stand boring people. - I can't stand boring people.

Can't say no- be unable to refuse

I can"t say no to your offer. - I can’t refuse your offer.

Can't wait- be unable to wait, burn with impatience

Children can't wait to go to the circus. - Children can't wait to go to the circus.

Don’t be intimidated by so many functions and meanings of the verb can, with practice it will become easier for you to distinguish between them, because you are already using most of them! To keep up to date with all the news on our website, we recommend that you subscribe to our newsletter and join us in

Modal verb can- one of the most common verbs in English language. It is most often used when you need to express opportunity to take some action, in other words, to say “I can do this,” “he can,” “you can,” and so on. Verb could is the past tense form of the verb can, which we will also look at in this article.

Table: modal verb Can in affirmative, negative, interrogative form

  • You can solve your problems later. - You can solve your problems later.
  • We can watch this movie next time. - We Can watch this movie next time.

Also, instead of the verb can, the phrase will be able to can be used to denote a possibility in the future; read more about this below.

2. To express a request.

Are used can And could in interrogative form. A request with could sounds a little more polite; it is used in sentences addressed to another person (that is, not with the pronoun I).

3. To express a prohibition.

Verb can't often used to express a prohibition, that is, to say not “you cannot,” but “you are not allowed.”

4. To express surprise, doubt, disbelief.

There are many nuances here, much depends on the context.

Doubt with a tinge of mistrust is more often expressed in negative sentences with a verb in an indefinite form:

  • He can't swim across Lake Tahoe. - Yes can not he swims across Lake Tahoe (distrust, doubt).

Surprise with a tinge of doubt and distrust is usually expressed in interrogative sentences with a verb in an indefinite form. In translation, the word “really” is often used to make the meaning clearer.

  • Can this unicorn be real? – Really is this unicorn real?

If in the same question we use could the meaning will change a little. You'll get something like:

  • Could this unicorn be real? – Could you this unicorn be real?

Often offers with can\could used ironically, with sarcasm, for example:

  • Could do you buy more milk? -And you are even more milky could not buy?
  • Could will you wake up any later? - And you are even later could not wake up?

But in this case, intonation and context are of great importance. One of the characters in the series “Friends,” Chandler, used similar phrases with “Could it be” so often that he was even sometimes imitated. Unfortunately, this feature of Chandler's speech was almost not reflected in the translation.

5. To express doubt about what happened

That is, I don’t believe that something happened. Scheme: cannot + have + Past Participle (affirmative or interrogative form).

The phrase is usually translated using “cannot be” or another suitable expression.

  • He is my best friend, he cannot have betrayed me. - He is my friend, it can't be that he betrayed me.
  • Billy doesn't have much money. He can't have bought this car. Billy doesn't have much money. He couldn't this car buy.
  • Can she have forgotten to pick up the kids from house? – Really she I might have forgotten pick up children from home?

Revolution could have + Past Participle

Separately, we should consider the phrase could have + (past participle, third form of the verb). It may mean:

1. An action that someone could have done but did not

  • She could have married him but she didn’t want to. - She could go out for him get married, but didn’t want to.
  • They could have bought a house here 20 years ago but chose not to. - They could buy house here 20 years ago, but decided not to do it.

There is often a hint of reproach involved.

  • You could have helped me instead of just sitting there. - You could help me instead of sitting here.
  • I could have done more to help you. Sorry. - I could do more to help you. Sorry.

2. Assumption, guess about something that happened in the past

In this case, with a slightly different meaning, can be used may have or might have, cm. " ".

  • Simon could have told her the truth. – Maybe, Simon told tell her the truth.
  • They could have overheard what we said. – They could hear what we said.

Can be used in negation and question can have + Past Participle, then you get a turn like “Really...?” or “It can’t be...”, discussed above (clause 5 “To express doubt about what happened”)

  • Can she have forgotten about our meeting? – How could I she forget about our meeting?
  • He can't have seen us. – Can't be so that he us saw.

3. Assumption about something that did not actually happen

This case belongs to one of the types conditional offers, read more about them in.

  • I could have done well in my exam if I had worked harder. – I could have done better in the exam if I had prepared better.

Modal verb can and phrase to be able to

Verb can in the meaning of “to be able to do something” can be replaced by a synonymous phrase to be able to+ verb (to be able to do something). But there is a difference between these two ways of expressing possibility.

Can\to be able to in the future tense

It is usually said that turnover to be able to convenient to use when you need to talk about the possibility of doing something in the future, because the verb can there is no future tense form (you cannot say will can).

But here it is important to remember this nuance.

The verb can itself can refer to the future. For example:

  • You can rest later. Now we have to work. - You you can(you can) rest later. Now we have to work.
  • We can read this book tomorrow, let's play videogames. - We we can(we can) read this book tomorrow, let's play video games.

In the future tense, be able to is used when we talk about an opportunity, ability, or skill that does not exist now, but will appear in the future. The verb can cannot be used to express a possibility, an ability that will only appear in the future.

  • Right: I will be able to walk properly after the surgery. - I I can Walking normally after surgery.
  • Wrong: I can walk properly after the surgery.
  • Right: will be able to work as a sailor. – When I finish these courses, I I can work as a sailor.
  • Wrong: When I complete this training course, I can work as a sailor.

Both options, can or to be able to, can be used when talking about decisions or agreements related to the future:

  • The doctor can\will be able to see you later today. - Doctor will be able see you later today.
  • I can\will be able to help you with your homework later. - I I can help you with your homework later.
  • I can\will be able to give you a lift home tonight. - I I can give you a ride home tonight.

Can\to be able to in the present tense

To be able to sounds more formal, even strange. It’s the same as saying in Russian not “I can play the guitar,” but “I’m capable of playing the guitar.”

  • I can play a guitar. - I Can to play guitar.
  • I am able to play a guitar. - I capable to play guitar.
  • Michelle can can bake delicious pies.
  • Michelle is able to bake delicious cakes. – Michelle capable bake delicious pies.

Variants with can are used much more often.

Can \to be able to in the past tense

When talking about an ability or opportunity that existed in the past, both options can be used:

  • When I was younger, I could could remember everything better.
  • When I was younger, I was able to remember everything so well. – When I was younger, I could remember everything better.

Please note that in the past tense could usually means (in affirmative sentences) the ability to do something in general and is not used when talking about some one-time action at a certain moment. It makes more sense here to be able to.

  • Right: We were able to visit Mary on Monday, because she wasn’t busy. - We were able to to visit Mary on Monday because she was not busy.
  • Wrong: We could visit Mary Monday, because she wasn’t busy.

IN negative sentences both couldn’t and wasn’t\weren’t able to can be used for both long-term actions and one-time ones.

  • I couldn't / wasn't able to finish all my homework yesterday. - I could not finish homework yesterday.
  • I couldn't / wasn't able to see the band at all from where I was standing. - I don’t really care wasn't visible(couldn't see) the musicians from where I was standing.
  • I couldn't / wasn't able to drive when I was younger. - I couldn't drive, when I was younger.

In addition to ordinary verbs in the English language, there are special verbs that are not similar to others, because they are not used by themselves, but only accompanied by ordinary verbs, do not change according to persons and are not subject to grammatical rules. They are called modal - that is, these verbs express not the action itself, but the attitude towards it. The main representatives of this group, the most common and most often used orally and writing are modal verbs can, may, must, and this article will be devoted to the first of the listed verbs - can- “to be able to, to be able to.” This verb, unlike other modal verbs, has the form of the present tense - can and the past tense - could.

General features of modal verbs

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As mentioned above, modal verbs do not follow general grammatical rules and they all have distinctive features.

  1. They do not change according to persons and numbers (that is, the same form for all persons - I can, she can)
  2. They do not require the use of an auxiliary verb, but themselves act as an auxiliary verb (not Do you can swim, but - Can you swim)
  3. After them the infinitive of the verb is used without the to particle(He can speak Chinese)

Conjugation of the modal verb Can in examples
Let's follow the affirmative, interrogative and negative forms of the modal verb can – could in the sentence “I can draw”

I can draw a picture - I can (could) draw a picture - I could draw a picture
We can draw a picture - we can (could) draw a picture - we could draw a picture
You can draw a picture - you can (could) draw a picture - you could draw a picture
He, she, it can draw a picture - he, she can (could) draw a picture - he, she, it could draw a picture

As you can see from the examples, the modal verb can (could) has only one form, which is suitable for all persons without exception and does not change.

The negative form is formed using the negative particle not, which is placed after the modal verb can not (can’t) and could not (couldn’t).

I cannot (can’t) / could not (couldn’t) draw a picture
We cannot / could not draw a picture
You cannot / could not draw a picture
He, she, it cannot / could not draw a picture

When forming an interrogative form, we use the modal verb can as an auxiliary verb and construct an interrogative sentence in the following sequence: 1) – question word (if any), 2) – auxiliary verb can/could, 3) – subject, 4) – predicate, 5) - minor members offers. Let's try to translate the following questions into English together:

Can you read German? – Can you read German? (a general question does not contain a question word, so the translation of the sentence begins with an auxiliary verb)
What can you cook for lunch? – What can you cook for dinner? (special question, contains a question word)
Who can fix the TV? – Who can repair the TV? (question to the subject - note that in this case the auxiliary verb is immediately followed by the predicate)

What does the modal verb can mean? When should you use it?

1) The modal verb can has several meanings, but its main purpose is to express the physical and mental ability of a person. when we speak “I can cook - I know how (can) cook”, we mean we have the skill to cook dinner. “I can open this box - I can open this box”, i.e. I have enough strength, I am physically strong enough to open this box.

We can help you solve examples – We can help you to do the summs (mental ability)
I can carry the luggage to the car (physical ability)

2) Using the modal verb can we express a prohibition, request or permission:

You cannot go out - you cannot go outside (ban)
Can I have dinner with you? — Can I have lunch with you? (request)
You can watch TV after you complete your lessons – You can watch TV when you finish your lessons (resolution)

3) Surprise, disbelief, doubt can also be expressed using the modal verb can. In this case, the sentence will more often be interrogative or negative, and the modal verb will more often be translated as “really.”

Could he cheat me? - Did he really deceive me?
I couldn’t have lost the money - I couldn’t lose money
How can you say such a thing! – How can you say such things!
She can't be 50! – Is she really 50 years old?

We often see the modal verb can accompanied by verbs of perception and feelings feel, see, hear, understand and others, but in this case we often do not translate the modal verb into Russian:

I can feel the flavor of roses - I feel the scent of a rose
Can you understand what I tell you? - Do you understand what I'm telling you?

To conclude this article, we suggest you remember constructions that contain the modal verb can:

It can’t be possibly true - It cannot be that this turns out to be true
I can’t but ask him about it - I have no choice but to ask him about it
I couldn’t help laughing - I couldn’t help but laugh

The verb can belongs to a group of verbs that have certain features.

In this article I will tell you how this group of verbs differs from the rest, in what cases we use can, consider the past form of this verb and learn how to build all types of sentences with it.

Features of the use of verbs expressing the speaker’s attitude

Can belongs to a group of verbs that express the speaker's personal attitude. For example: opportunity, desire, duty, necessity, readiness.

Such verbs have a number of features that distinguish them from other verbs in the English language:

1. They are independent verbs.

With them you do not need to use do, does, did, will, etc. to ask a question or construct a negation. Not is added to them (in negation). And in questions they are placed first in the sentence.

He does not can fly.
He can't fly.

He cannot fly.
He can't fly.

Does he can fly?
Can he fly?

Can he fly?
Can he fly?

2. The particle to is never placed after such verbs.

He can't fly.
He can fly.

He canfly.
He can fly.

3. These verbs do not change their ending depending on actor

He can't fly.
He can fly.

He can fly.
He can fly.

Use of the verb can in English

The verb can is translated as “I can.” We use it when we talk about the present tense.

The verb can is used in the following situations:

1. When we talk about mental or physical ability
(I can swim, I can solve an equation)

I can dance.
I Can dance.

Tony can run fast.
Tony Maybe run fast.

2. When we ask permission to do something or ask about a request
(can I open the window, can I ask a question)

Can I look at this document?
Can should I take a look at this document?

Can she bring me coffee?
Maybe will she bring me coffee?

3. When we talk about the possibility of doing something
(I can help you, I can bring it)

4. When we talk about the likelihood that something will happen
(he might be late, it might be hard)

The verb can is in the past tense

The verb can has the past tense form could, which translates as “could”.

Could is used in the following situations:

1. To express the possibility or ability to do something in the past.
(could have tried, could have played all day as a child)

I could help.
I could help.

He could speak French.
He could To speak French.

Pay attention e: Could is used in another meaning that has nothing to do with the past tense. It is used:

2. To ask permission or express a request in a more polite manner than with can.
(could you close the window, could you bring me some water)

Could are we sitting?
Could should we sit down?

Could did you call Tom?
Could would you call Tom?

Could can you help me?
Could would you help me?

This form is very actively used when traveling when you ask strangers tell you something or help you.

Affirmative sentences with the verb can/could

Affirmative sentences - when we affirm something, that is, we say that someone can/could do something.

The verb can is independent on its own, so it does not require other auxiliary verbs. Also remember that it does not change in any way depending on the character. The sentence formation scheme will be like this:

The one in question + can/could + action

I
You
We dance
They can/could swim
She cook
He
It

You can invite other people.
You can invite other people.

He could kiss her.
He could kiss her.

Negative sentences with the verb can/could

By using this verb in a negative sentence, we say that someone does something can't/couldn't. In this case, we add the negative particle not to can. Sentence formation scheme:

The one in question + can/could + not + action

I
You
We dance
They can/could not swim
She cook
He
It

Note: Can and the particle not are written in one word, that is, we do not put a space between them: cannot.

She cannot stop crying.
She can not stop crying.

I could not go to the cinema.
I couldn't go to the cinema.

Abbreviations:

When negated, we can use the following abbreviations:

can + not = can’t

could + not = couldn’t

I cant answer your question.
I I can not answer your question.

She couldn'tt leave a lesson.
She I could not leave the lesson.

Interrogative sentences with the verb can/could


To ask someone if they can do something, we need to be able to construct interrogative sentences. To ask the question can we put it first. Sentence formation scheme:

Can/could + the person in question + action?

I
you
we dance?
Can/could they cook?
she swim?
he
it

Can are we talking?
Can shall we talk?

Could do you explain this rule?
Could could you explain this rule to me?

When answering, you can use can/cannot:

Yes, I can.
Yes I can.

No, I cannot.
No I can not.

As well as other expressions that are appropriate in meaning. For example:

Of course.
Certainly.

Sure.
Certainly.

I think so.
I think yes.

I doubt it.
I doubt.

I'm afraid not.
I'm afraid not.

Interrogative sentences with clarifying words

To clarify any information we are interested in, we can use the following words when we ask the question:

  • What - what
  • Where - where
  • Who - who
  • Which - which
  • Why - why
  • When - when

To construct a question with these words, we put them in first place, the rest of the word order remains as in a regular question. Scheme for forming such a question:

Clarifying words + can/could + the person in question + action?

I
you
What we write?
Where can/could they cook?
When she dance?
he
it

When can you call me?
When can you call me?

What could I tell him?
What could I tell him?

So, today we got acquainted with the verb can, which has certain features in its use. If you still have any questions, feel free to ask them in the comments. Now is the time to move on to practice.

Reinforcement task

Translate the following sentences into English. Leave your answers in the comments below the article, and I will answer them.

1. Can you remind me to take an umbrella? Yes I can.
2. He could have warned you.
3. They cannot swim across this river.
4. Could you wait? Yes, I could wait.
5. She couldn't speak English.
6. Can your friends turn off the music? No, they can't turn off the music.
7. He can drive a car.
8. Can she sing a song?

Modal verb can is one of the most used modal verbs in the English language. It has the meaning of ability or ability, both physical and mental. It can be used to express a request, permission or prohibition, and probability or improbability.

For example:
I can ride a horse.
I I can ride a horse. ( Expresses ability.)

We can stay with my brother when we are in Paris.
When we are in Paris, we Can stay with my brother. ( Expresses possibility.)

She cannot stay out after 10 pm.
She can not walk after 10 pm. (Expresses prohibition.)

Can you hand me the stapler?
Not can can you pass me the stapler? ( Expresses a request.)

Any child can grow up to be president.
Any child Maybe grow up and become president. ( Expresses probability.)

Using the modal verb can in the present, past and future tenses

In most cases, the use of modal verbs in the past and future tenses is different from other verbs. The table below shows use of a modal verb can in different situations.

Usage Affirmative forms
1. Real
2. Past
3. Future
Negative forms
1. Real
2. Past
3. Future
Synonyms
can
in the sense of ability in general
1. I can speak Chinese.
I I can to speak Chinese.

2. Changes to " could"
I could speak Chinese when I was a kid.
When I was a child I knew how to speak Chinese.

3. Changes to " be able to"
I will be able to speak Chinese by the time I finish my course.
When I finish the course I will be able to to speak Chinese.

1. I can"t speak Swahili.
I I do not know how speak Swahili.

2. Changes to " could"
I couldn't speak Swahili.
I couldn't speak Swahili.

3. Changes to " be able to"
I won't be able to speak Swahili.
I I can not speak Swahili.

be able to
can
in the sense of ability during any specific time, event
1. With a burst of adrenaline, people can pick up cars.
During an adrenaline rush, a person Maybe lift the car.

2. Changes to " be able to"
With a sudden burst of adrenaline, he was able to
smog

3. Changes to " be able to"
With a sudden burst of adrenaline, he will be able to lift the car.
During the adrenaline rush, he will be able lift the car.

1. Even with a burst of adrenaline, people can"t pick up something that heavy.
Even during an adrenaline rush, people can not lift such heavy things.

2. Changes to " could"
Even the weight lifter, couldn't lift the car off the child's leg.
Even a weightlifter couldn't lift the car off the child's feet.

3. Changes to " be able to"
Even three men working together won't be able to lift the car.
Even three men all together they won't be able to lift the car.

be able to
can
in the sense of possibility
1. I have some free time. I can help her now.
I have some free time, now I Can help her.

2. Changes to " be able to"
I had some free time yesterday. I was able to help her at that time.
Yesterday I had some free time and I smog help her.

3. I"ll have some free time tomorrow. I can help her then.
Tomorrow I will have some free time, and then I I can help her.

1. I don't have any time. I can"t help her now.
I don't have any time. Now I I can not help her.

2. Changes to " be able to"
I didn't have time yesterday. I wasn't able to help her at that time.
Yesterday I had no time at all, and I couldn't help her.

3. I won't have any time later. I can"t help her then.
Later I won't have any time at all and I'll I can not help her.

be able to
can
in the meaning of permission, permission
1. I can
I Can(= me Can

2. Changes to " be allowed to"
I was allowed to
Last week I could(= me it was possible

3. I can
Next week I I can(= me it will be possible

1. I can"t drive Susan's car when she is out of town.
I I can not(= me it is forbidden) drive Susan's car while she's out of town.

2. Changes to " be allowed to"
I wasn't allowed to drive Susan's car while she was out of town last week.
Last week I could not(= me it was impossible) drive Susan's car while she was out of town.

3. I can"t drive Susan's car while she is out of town next week.
Next week I I can not(= me it won't be possible) drive Susan's car while she's out of town.

be allowed to, may
can
in the meaning of a request
Can I have a glass of water?
Can Should I have a glass of water?

Can
Can drop me off at school?

Can't I have a glass of water?
Should I it is forbidden glass of water?

Can't do you give me a lift to school?
Are you can not drop me off at school?

Requests usually relate to the near future.

could, may
can
in the sense of probability or non-probability
Anyone can become rich and famous if they know the right people.
Any Maybe to become rich and famous if he has acquaintances for this.

Learning a language can be a real challenge.
Language learning Maybe be very difficult.

It can"t cost more than a dollar or two.
Can't be for it to cost more than a couple of dollars.

You can"t be 45! I thought you were about 18 years old.
You can not be 45 years old! I thought you were about 18.

Usually a generalization or assumption.

could

Sometimes verb can can be used in a negative and interrogative form to express a small, doubtful probability, as well as annoyance and bewilderment, as, for example, in the last two sentences of the above table (It can"t cost more than a dollar or two. and You can"t be 45! I thought you were about 18 years old.)

For example:
Can he have gone?
Really he left? (= Can't be so that he leaves.)

In the same cases, the modal verb could can be used, for example:

She can"t (= couldn't) have said it.
She I could not to say this. (= Can't be for her to say it.)

Also verbs can And could can be used with verbs of feeling and perception ( see, smell, taste, understand, feel, hear etc.) to give a hint of effort in performing an action, expressed semantic verb. When translated into Russian, the modal meaning is not emphasized.

For example:
Can you see that house?
See this house?

Can you hear that strange noise?
You do you hear this strange noise?