Using Perfect Infinitives with Modal Verbs | English Grammar

The structure “have + past participle” is called a perfect infinitive.

In this lesson, we will learn about the combination between modal verb and perfect infinitive.

Using Perfect Infinitives with Modal Verbs




  • to refer to the past
  • to refer to unreal situations
  • to show that the activity was different from what we wanted
  • to say how confident we are that something has happened

Perfect Infinitives with Modal VerbsPin

Perfect Infinitives with Modal VerbsPin

Must + Have + Past Participle

Express deduction, a logical conclusion, probability

  • It is very cold; it must have snowed in the mountains.
  • If you can’t find your car keys, you must have left them in the house.

Can’t/Couldn’t + Have + Past Participle

Express negative deduction (impossibility in the past)

  • She can’t have passed such a difficult exam. 

Could + Have + Past Participle

Express past reference about something that was not carried out

  • You could have done it. (You didn’t do it)  
  • She could have called the doctor early in the morning. (She didn’t call the doctor)

Perfect Infinitives with Modal VerbsPin

May + Have + Past Participle

Express the possibility that an action took place in the past

  • The little girl may have lost the key. (It is possible that she lost the key.)  

Might + Have + Past Participle

Express a past possibility

  • Our neighbours might have heard some noises when our car was stolen.

Perfect Infinitives with Modal VerbsPin

Needn’t + Have + Past Participle

Express an unnecessary action, which was, nevertheless, performed

  • needn’t have knocked at the door since, in this way, I awoke the baby. (But I knocked)
  • You needn’t have bought the flowers.

Perfect Infinitives with Modal VerbsPin

Should + Have + Past Participle

Indicate that the past obligation was not fulfilled or carried out

  •  You should have locked the door before leaving the house. (But you didn’t lock it.) 

Should + Have + Past ParticiplePin

Ought to + Have + Past Participle

Express an unfulfilled duty or obligation

  •  Paul ought to have waited until the lights were green before he crossed  the street. (But he didn’t wait.)

Should + Have + Past ParticiplePin

Would + Have + Past Participle

The third conditional

  • would have gone to university if my parents had had more money. (The speaker didn’t go to university.)

Would + Have + Past ParticiplePin

Perfect Infinitives with Modal Verbs | Image

Perfect Infinitives with Modal VerbsPin

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hernan suarez
hernan suarez
3 years ago

is a excelent page ,i can learn more easy

joel koma
joel koma
2 years ago

l can now speak english with grammer due to this page.

Raj Sharma
Raj Sharma
1 year ago

You are rendering very useful tips for learners of the language. The colorful charts are so tempting. Thanks.

Maria khurshid
Maria khurshid
10 months ago

It can make learning easy

8 months ago

Could you applaud the model verb should be exercise?

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