Can
We use the auxiliary verb "can" in these situations:
She can swim very well.
He can speak five languages.
Mistakes can happen to anyone.
Friends can help you feel better when you're sad.
You can't smoke here.
Can I take a photograph?
Can you help me with my homework?
Can you open the window, please?
Let's take a look at the different forms of the auxiliary verb "can" in positive and negative statements and questions.
POSITIVE STATEMENTS
I can do ...
You can do ...
She can do ...
He can do ...
It can do ...
We can do ...
You can do ...
They can do ...
NEGATIVE STATEMENTS
I cannot / can't do ...
You cannot / can't do ...
She cannot / can't do ...
He cannot / can't do ...
We cannot / can't do ...
You cannot / can't do ...
They cannot / can't do ...
POSITIVE QUESTIONS
Can I do ...?
Can you do ...?
Can she do ...?
Can he do ...?
Can it do ...?
Can we do ...?
Can you do ...?
Can they do ...?
NEGATIVE QUESTIONS
Can I not / Can't I do ...?
Can you not / Can't you do ...?
Can she not / Can't she do ...?
Can he not / Can't he do ...?
Can it not / Can't it do ...?
Can we not / Can't we do ...?
Can you not / Can't you do ...?
Can they not / Can't they do ...?
SHORT ANSWERS
Yes, I can. / No, I can't.
Yes, you can. / No, you can't.
Yes, she can. / No, she can't.
Yes, he can. / No, he can't.
Yes, it can. / No, it can't.
Yes, we can. / No, we can't.
Yes, you can. / No, you can't.
Yes, they can. / No, they can't.
As you can see, the auxiliary verb "can" is used to make negative sentences and questions.
+She can play the piano.
-She cannot / can't play the piano.
+?Can she play the piano?
-?Can she not / Can't she play the piano?
Yes, she can. / No, she can't.
After the auxiliary verb "can", we use the base form of a verb, which does not take either the third person singular "s", "-ed", or "-ing". We cannot put "to" before "can" either.
She cans plays the piano well.
In negative sentences, it is more common to write "cannot" as one word with no space in between.
Exercises
Complete each sentence with the correct form of "can" and a verb from the list below.open | tell | see | play | use | catch
1.I'm sorry, I ____ you on the weekend. I'm so busy.
I'm sorry, I can't see you on the weekend. I'm so busy.
2.Excuse me, I think I'm lost. ____ I ____ your cell phone to call my parents?
Excuse me, I think I'm lost. Can I use your cell phone to call my parents?
3.It's too hot. ____ I ____ the window?
It's too hot. Can I open the window?
4.The dog is so smart. It ____ the ball when I throw it.
The dog is so smart. It can catch the ball when I throw it.
5.We ____ together after school if you want.
We can play together after school if you want.
6.____ you ____ me how to get to the library from here?
Can you tell me how to get to the library from here?