Should / Ought to / Must Have V3

Comparison of Should (Ought to) Have V3 and Must have V3

These two expressions are confused even by advanced English students. They do have different meanings and usage so we've tried to explain the differences for clarification.

Also See:

Could Should Would Must Have
Needn't Have / Didn't Need(Have) to

Subject Exercise:
Should Have/Must Have Exercise

Should (Ought to) Have Done (V3)

Should have + past participle talks about past events, actions that did not happen but it would be better if they had happened. A mistake or regret is implied.

For Example:

You should (ought to) have checked your report thoroughly before you handed it in.

You should (ought to) have asked my permission before you used my computer. I’m really angry with you.


We use third form (verb3) of the verb after the modal "Should / Ought to have." (Ought to being a little stronger)

They should(Ought to) have listened to me and bought that house last year before the prices increased.

You shouldn't have been watching TV all night yesterday, that’s why you feel so tired now.


In negative form, "Ought to" becomes "Ought not to". Do not contract oughtn't.

Must Have Done (V3)

Modal "must" has a meaning of necessity, many think that "must have V3" has the same meaning as "should have V3". However; We use must when we talk about a strong possibility based on facts referring to the past.

For Example:

I saw Cynthia crying a few minutes ago. She must have heard the bad news.

I'm quite sure that I put my phone on my desk, now that it's not there somebody must have taken it.

A: Do you know where Martin is?
B: I haven't seen him, but I'm sure he must have left the office as it's 5 o'clock already.


Both "must have" and "should have" are perfect modals and they should be followed by past participle (verb3)

They mustn't have arrived (arrive) early, or else they would have called us.

He shouldn't have dropped (drop) out of the school. She regrets doing so now.

What’s New on GrammarBank:

  1. Second Conditional IF Exercise – GrammarBank

    Feb 20, 18 12:47 AM

    Second conditional (type two) grammar exercise with answers -- Check your answers at the bottom of the worksheet.

  2. Second Conditional IF Exercise 2 – GrammarBank

    Feb 20, 18 12:43 AM

    Second conditional (type two) grammar exercise with answers 2 -- Check your answers at the bottom of the worksheet.

  3. How Much vs How Many Exercise 2 - GrammarBank

    Feb 17, 18 05:06 AM

    Printable and online grammar exercises-- How Much vs How Many worksheets with answers

  4. Unless / IF Not - GrammarBank

    Feb 17, 18 04:29 AM

    Unless means except if. We use unless to make an exception to something we say. See details with examples and exercises.

  5. First Conditional IF Exercise – GrammarBank

    Feb 14, 18 09:57 AM

    If conditional type 1 (first conditional) grammar exercise with answers-- Check your answers at the bottom of the worksheet.

  6. In Case - GrammarBank

    Feb 14, 18 03:36 AM

    Uses of In Case, detailed rules explanations with examples and exercises for English learners and teachers

  7. Wish Clauses - GrammarBank

    Feb 14, 18 03:32 AM

    Uses of Wish Clauses, grammar rules with examples, exercises, and detailed explanations.

  8. IF clauses / IF Conditionals - GrammarBank

    Feb 14, 18 03:26 AM

    IF clauses / First, Second and Third Conditionals (Type 1, type 2, type 3) categories explained with details, examples and exercises

  9. Third Conditional IF - GrammarBank

    Feb 14, 18 03:22 AM

    Third conditional if is used for unreal situations in the past. Type three conditional grammar, with examples and exercises

  10. Second Conditional IF - GrammarBank

    Feb 14, 18 03:21 AM

    Second conditional IF also referred as Type 2 conditional is used for...See second conditional rules, examples and exercises