Can't and couldn't: negative sentences
530 fill-in-the-gap exercises, 53 tests of ten
Add not to the modal. Cannot is written as one word; the short form is can't.
Practice this form
Loading…
Getting your first question ready.
The pattern
Not attaches to the modal, and can is the only English verb whose full negative is written as a single word: cannot.
She cannot attend. — formal writing. She can’t attend. — everything else.
Could not stays as two words, shortening to couldn’t.
can’t as impossibility
This is the meaning learners meet less often, and it matters:
He can’t be at home — I’ve just seen him at the office.
Here can’t is a conclusion, not a statement about ability. The positive version uses must:
He must be at home; the lights are on.
For the past, use can’t have and must have:
She can’t have heard you. He must have left early.
couldn’t works for both kinds of past
Unlike the positive, the negative does not need wasn’t able to:
He couldn’t open the door. — whether it was a general inability or one particular failure.
Refusals and rules
Can’t is the everyday way to state a rule:
You can’t park here between eight and six.
It is blunter than mustn’t in some contexts and softer in others, and both are widely used on signs.
All forms
| Full form | Short form | |
|---|---|---|
| present | cannot swim | can't swim |
| past | could not swim | couldn't swim |
Examples
Taken from the 530 sentences in this drill. The answer is highlighted.
- They couldn't sleep well all last week because of the noisy neighbors.
- I can't go out after dark without my glasses, and my eyes are getting worse.
- She couldn't play the violin beautifully in her first recital.
- We can't wait for them any longer; our table is booked for seven.
- They couldn't swim across the river without a life jacket that summer.
- My parents can't afford to buy a new car right now.
- They couldn't find a solution to the problem at yesterday's meeting.
- We can't go on vacation this year due to financial constraints.
- The dog couldn't find its bone in the tall grass.
- The baby can't reach the cookie on the table, and she is trying hard.
- Mark couldn't play the guitar when he was younger.
- He can't drive because he doesn't have a license.
Mistakes to avoid
Wrong: She doesn't can come. correct: She can't come.
Modals make their own negative.
Wrong: I can not swim. correct: I cannot swim. / I can't swim.
The full form is written as one word: cannot.