Lesson

Could (do) and could have (done)

Possibility and regret

≈ 15 min 8 block(s)

Text

Could (do) and could have (done)

This lesson explains the difference between 'could' + base verb (could do) and 'could have' + past participle (could have done). Both forms relate to ability, possibility, requests and suggestions, but they refer to different times and meanings.

  • 'Could' + base verb: present ability/possibility, past ability, polite requests or suggestions.
  • 'Could have' + past participle: talks about past possibilities, unreal past actions, or actions that did not happen.
  • Learn to choose the correct form depending on whether you talk about the present/future, the past, or a hypothetical situation.

Table

Could vs Could have: Forms and Uses

Form Use Example
could + base verb Present/future possibility, polite request, general past ability Could you send the report? / I could help with editing tomorrow. / When I was young I could speak German.
could have + past participle Past possibility/unreal past (something that did not happen) or criticism/regret about past We could have finished earlier if we had started on time. / You could have told me about the delay.
negative: could not (couldn't) / couldn't have Impossible past / denied possibility / inability She couldn't attend the meeting yesterday. / He couldn't have known about the error.
modal structure Modal verb + base verb; for past possibility add 'have' + past participle can → could (past); could have + done (past possibility)

Tip

Key rule: Time and meaning

Choose 'could' or 'could have' by deciding whether you talk about present/future, past ability, or a past hypothetical/unreal situation.

  • Use 'could' + base verb for polite requests, suggestions, or general ability (present or past). Example: 'Could you review this?' / 'I could speak French when I was a child.'
  • Use 'could have' + past participle to describe a past possibility that did not happen or to express regret/criticism. Example: 'We could have closed the deal if we'd negotiated better.'
  • For negatives: 'couldn't' (not able) vs 'couldn't have' (it was impossible that...).

Focus on the time reference: present/future → could; unreal past/possible but didn't happen → could have.

Example

Examples in context

Could you send the revised contract by Friday?

I could attend the client call tomorrow if my schedule is clear.

We could have avoided the delay if the vendor had delivered on time.

You could have mentioned the budget issue during the meeting.

Tip

Common mistakes to avoid

These are frequent, universal errors learners make when using 'could' and 'could have'.

  • Using 'could have' when you mean a present or future possibility (wrong time reference).
  • Missing the past participle after 'have' (e.g., 'could have went' instead of 'could have gone').
  • Confusing 'couldn't' (not able) with 'couldn't have' (impossible that something happened).
  • Using double modals or extra auxiliaries (e.g., 'could have been able to' when unnecessary).
  • Mixing up criticism and advice: 'could have' can sound like criticism if used about past actions.

Check time reference, verb form (past participle), and intended tone (suggestion vs criticism).

Quiz

Choose the correct sentence:

Hint: Think about a past possibility that required a prior condition

Quiz

Complete: He _____ the report on time if he had left the office earlier.

Hint: Think about a past possibility that didn't occur

Quiz

Which sentence expresses a past unreal possibility (something that did not happen)?

Hint: Look for a past structure that talks about what might have happened

Key Points

GrammarPoint

could

modal verb CEFR B1 //kʊd//

A modal verb used for past ability, polite requests, or present/future possibility.

Could you join the call at 2 PM?

GrammarPoint

could have

modal phrase CEFR B2 //kʊd hæv//

Used to describe a past possibility or hypothetical situation that did not occur.

We could have won the contract with a better proposal.

GrammarPoint

past participle

grammar term CEFR B1 //pæst ˈpɑːrtɪsɪpəl//

The verb form used after 'have' to form perfect tenses (e.g., finished, written).

The team had completed the audit before the meeting.

Expression

polite request

expression CEFR A2 //pəˈlaɪt rɪˈkwest//

A phrase used to ask for something in a respectful way ('Could you...').

Could you review this section before lunch?

Vocabulary

ability

noun CEFR B1 //əˈbɪlɪti//

The power or skill to do something; often expressed with can/could.

She has the ability to manage multiple projects.

Vocabulary

regret (about past action)

noun CEFR B2 //rɪˈɡrɛt//

A feeling of disappointment about something that happened; often expressed with could have.

He expressed regret: 'We could have improved the proposal.'