HomeGrammarGrammar worksheets and testAdvancedModals: can't have/ must have / might have

Modals: can't have/ must have / might have


Introduction

We use the modal verbs "must have", "can't have" and "might have" to make guesses or deductions about an action in the past that we believe has definitely happened, has definitely not happened or possibly happened, based on our knowledge, information or evidence, or lack of it.

We use "must have", "can't have" and "might have" in the same way as the present perfect - the action we are describing happened, or did not happen, in the past and is still true in the present.

Form

We use "must have", "can't have" and "might have" with the past participle of the main verb:


likelihood of the deduction Subject modal main verb (past participle)
definite I
You
We
They
He / She / It
must have been
seen
taken
spoken
to France.
the movie.
the medicine.
to the manager.
definitely not can't have
possible might (not) have

Positive and negative forms

We use "must have" in the positive form only: we believe that the action definitely happened.

We use "can't have" in the negative form only: we believe that the action definitely did not happen (the opposite of "must have").

We can make a negative form of "might have" with "not": we believe it is possible that the action did not happen, but it is also possible that it did. "might not" can be contracted to "mightn't".

Using "by now" and "yet"

We can use "by now" with positive forms e.g.
We can use "yet" with negative forms e.g.

Question form

We don't use "must have" or "can't have" in question form because we use them for definite beliefs. We use "might have" for question forms:

Positive question form

modal Subject "have" main verb (past participle)
Might I
you
we
they
he / she / it
have been to France?

Practice

Complete the sentences with "can't have", "must have" or "might (not) have" using the verb in brackets:

  • He hard for his exams because his results were very good. (study)
     
  • They the instructions because they looked confused. (not understand)
     
  • She home late last night because she was very tired this morning. (get)
     
  • they to the wrong place? (go)
     

Further practice

Complete the sentences with the correct answer from a, b, c or d:



Check my answers

Further language point - "might have" with "not"

"might have not"

In addition to the most common form "might not have" (described above), it is also possible to use the form "might have not": In the second sentence, "not" is used to emphasise the negative of the main verb; in this case, "might have" describes a positive possibility that he did not send the invitations.
Negative question form

We can also use "might not have" to form questions. We can change the position of "not" to make different emphases:

modal Subject "have" main verb (past participle)
Might I
you
we
they
he / she / it
not have been to France?
have not
Mightn't have




Vocabulary
 

Vocabulary


Vocabulary exercises:Expand your vocabulary using our three vocabulary trainers:Practice your spelling using our three spelling tests:Practice vocabulary relating to graphs and charts:
Learn vocabulary
Reading exercises
 

Reading exercises



Improve your reading skills:
 
Go to reading exercises
Video lessons
 

Video lessons


Focus on specific areas of business English using our video lessons:
 
Take a video lesson

Create an account
Access by account type:

Getting Started
Free
Create account
Vocabulary
 
Business English vocabulary exercises - save your score
 
General vocabulary trainer – save your score, access audio files
 
Business vocabulary trainer
 

Idiom trainer
 

Spelling tests
 

Graphs and charts practice
 

Grammar
 
Grammar test - save your score
 
Verb conjugation practice
 

Conditionals practice
 

Reading exercises
 
Reading exercises
 

Listening exercises
 
Listening exercises (short-form) - save your score
 
Listening exercises (long-form)
 

Dictation exercises
 
3 scenario-based exercises
 
52 additional scenario-based exercises
 

Focus on grammar
 

Numbers
 

Video lessons
 
4 video lessons
 
10 additional video lessons
 

Getting Started
Free
Create account
 
Vocabulary
 
Business English vocabulary exercises - save your score
General vocabulary trainer – save your score, access audio files
Business vocabulary trainer

Idiom trainer

Spelling tests

Graphs and charts practice

 
Grammar
 
Grammar test - save your score
Verb conjugation practice

Conditionals practice

 
Reading exercises
 
Reading exercises

 
Listening exercises
 
Listening exercises (short-form) - save your score
Listening exercises (long-form)

 
Dictation exercises
 
3 scenario-based exercises
52 additional scenario-based exercises

Focus on grammar

Numbers

 
Video lessons
 
4 video lessons
10 additional video lessons