The negative form of can: cannot/can't
1. Basic Usage
1. Indicates ability (in terms of physical and mental capacity) to do or to happen, meaning “can, able to,” etc., generally indicating present ability, for example:
They could speak English at a very young age.
They could speak English at a very young age.
Peter can type 100 words per minute.
Peter can type 100 words per minute.
Can you speak English?
Can you speak English?
Can you play the piano?
Can you play the piano?
The stadium can be emptied in four minutes.
The stadium can be emptied in four minutes.
However, when we make a current decision about future ability, we can use can, for example:
I can’t promise anything, but I’ll do what I can.—->future
I can’t promise anything, but I’ll do what I can.
A: Can you help me with my homework?—->now
A: Can you help me with my homework?
B: Sorry. I’m busy today. But I can help you tomorrow.—->future
B: Sorry. I’m busy today. But I can help you tomorrow.
2. Indicates requests or permission, often used in spoken language, meaning “can, able to,” etc. Used in interrogative sentences to make requests, and in negative sentences to indicate prohibition. For example:
Can I read your newspaper?
Can I read your newspaper?
You can’t play basketball.
You can’t play basketball.
We can’t wear jeans at work.
We can’t wear jeans at work.
Can you…?” means “Could you…?” indicating the speaker’s request; Can I…?” means “May I…?” asking for permission.
Can you help me with this box?
Can you help me with this box?
Adding the word please at the end makes it more polite. For example:
Can you feed the cat, please?
Can you feed the cat, please?
3. Indicates possibility. For example:
The moon can’t always be full.
The moon can’t always be full.
That can’t be Mary─she’s in New York.
That can’t be Mary─she’s in New York.
He can’t have slept through all that noise.
He can’t have slept through all that noise.
4. Indicates doubt. When expressing this meaning, it can only be used in general questions and carries emotional connotation. For example:
2. Sentence transformations are as follows:
1. When forming negative sentences, simply add “not” after can, which can be contracted to can’t or cannot, but cannot be written as cann’t. For example:
He can swim. —-> He can’t swim.
He can swim. —-> He can’t swim.
Emma can see the pen on the desk.—->Emma cannot see the pen on the desk.
Emma can see the pen on the desk.—->Emma cannot see the pen on the desk.
2. When forming general questions, simply move it before the subject (the first letter of the original subject is changed to lowercase, and the first person should be changed to the second person). For example:
I can see an orange on the table. —->Can you see an orange on the table?
I can see an orange on the table. —-> Can you see an orange on the table?
The response can be affirmative with Yes, OK, or Certainly; negative with No or Sorry. For example:
A: Can you look after my books, please?
A: Can you look after my books, please?
Using Certainly as a response makes the tone more affirmative. For example:
A: Can I see your guitar?
A: Can I see your guitar?
Can and may can both express “permission.” When asking for someone’s opinion, may is used more often. For example:
When inquiring whether it is objectively possible, can is preferred. For example:
Can we take the books out?
Can we take the books out?
When both can be used, may sounds a bit more polite. For example:
May I take this seat? Is slightly more polite than Can I take this seat?
Can also indicates ability, which may does not.
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