INGLÊS DE GRAÇA: Modal Verb

Modal Verb

CAN

Can is an auxiliary verb, a modal auxiliary verb. We use can to:

talk about possibility and ability
make requests
ask for or give permission

Structure of Can

subject + can + main verb
The main verb is always the bare infinitive (infinitive without "to").

	subject	auxiliary verb	main verb
+	I	can	play	tennis.
-	He	cannot	play	tennis.
-	He	can't	play	tennis.
?	Can	you	play	tennis?

Notice that:

Can is invariable. There is only one form of can.
The main verb is always the bare infinitive.

The main verb is always the bare infinitive (infinitive without "to"). We cannot say:

Use of Can

can: Possibility and Ability

We use can to talk about what is possible, what we are able or free to do:

She can drive a car.
John can speak Spanish.
I cannot hear you. (I can't hear you.)
Can you hear me?

Normally, we use can for the present. But it is possible to use can when we make present decisions about future ability.

Can you help me with my homework? (present)
Sorry. I'm busy today. But I can help you tomorrow. (future)

can: Requests and Orders

We often use can in a question to ask somebody to do something. This is not a real question - we do not really want to know if the person is able to do something, we want them to do it! The use of can in this way is informal (mainly between friends and family):

Can you make a cup of coffee, please.
Can you put the TV on.
Can you come here a minute.
Can you be quiet!

can: Permission

We sometimes use can to ask or give permission for something:

Can I smoke in this room?
You can't smoke here, but you can smoke in the garden.

(Note that we also use could, may, might for permission. The use of can for permission is informal.)

"Can" is one of the most commonly used modal verbs in English. It can be used to express ability or opportunity, to request or offer permission, and to show possibility or impossibility.

Examples:

I can ride a horse. ability
We can stay with my brother when we are in Paris. opportunity
She cannot stay out after 10 PM. permission
Can you hand me the stapler? request
Any child can grow up to be president. possibility

Using "Can" in Present, Past, and Future

Most modal verbs behave quite irregularly in the past and the future. Study the chart below to learn how "can" behaves in different contexts.

Modal Use	Positive Forms 1. = Present 2. = Past 3. = Future	Negative Forms 1. = Present 2. = Past 3. = Future	You can also use:
can general ability	1. I can speak Chinese. 2. SHIFT TO "COULD" I could speak Chinese when I was a kid. 3. SHIFT TO "BE ABLE TO" I will be able to speak Chinese by the time I finish my course.	1. I can't speak Swahili. 2. SHIFT TO "COULD" I couldn't speak Swahili. 3. SHIFT TO "BE ABLE TO" I won't be able to speak Swahili.	be able to
can ability during a specific event	1. With a burst of adrenaline, people can pick up cars. 2. SHIFT TO "BE ABLE TO" With a sudden burst of adrenaline, he was able to lift the car off the child's leg. 3. SHIFT TO "BE ABLE TO" With a sudden burst of adrenaline, he will be able to lift the car.	1. Even with a burst of adrenaline, people can't pick up something that heavy. 2. SHIFT TO "BE ABLE TO" Even the weight lifter, couldn't lift the car off the child's leg. 3. SHIFT TO "BE ABLE TO" Even three men working together won't be able to lift the car.	be able to
can opportunity	1. I have some free time. I can help her now. 2. SHIFT TO "BE ABLE TO" I had some free time yesterday. I was able to help her at that time. 3. I'll have some free time tomorrow. I can help her then.	1. I don't have any time. I can't help her now. 2. SHIFT TO "BE ABLE TO" I didn't have time yesterday. I wasn't able to help her at that time. 3. I won't have any time later. I can't help her then.	be able to
can permission	1. I can drive Susan's car when she is out of town. 2. SHIFT TO "BE ALLOWED TO " I was allowed to drive Susan's car while she was out of town last week. 3. I can drive Susan's car while she is out of town next week.	1. I can't drive Susan's car when she is out of town. 2. SHIFT TO "BE ALLOWED TO " I wasn't allowed to drive Susan's car while she was out of town last week. 3. I can't drive Susan's car while she is out of town next week.	may
can request	Can I have a glass of water? Can you give me a lift to school? Requests usually refer to the near future.	Can't I have a glass of water? Can't you give me a lift to school? Requests usually refer to the near future.	could, may
can possibility, impossibility	Anyone can become rich and famous if they know the right people. Learning a language can be a real challenge. This use is usually a generalization or a supposition.	It can't cost more than a dollar or two. You can't be 45! I thought you were about 18 years old. This use is usually a generalization or a supposition.	could