Past Modals: Must, May, Might, Could, Can't

This page introduces the concept of past modals and their usage in making deductions or speculating about past actions. It explains the structure and meaning of different modal verbs when combined with "have" and a past participle.

Definition: Past modals are used to express degrees of certainty about past events or actions.

The page presents a visual representation of the certainty levels associated with different modal verbs:

• Must have + past participle: Very possible (90% certainty)
• May/Might/Could have + past participle: Possible (50% certainty)
• Can't/Couldn't have + past participle: Impossible (0% certainty)

Example: "I must have left my phone in my house" expresses high certainty about the location of the phone.

The guide also provides a comparison of tenses with modal verbs:

• Present: Modal verb + infinitive
• Present Continuous: Modal verb + be + -ing
• Past Simple: Modal verb + have + past participle
• Past Continuous: Modal verb + have been + -ing

Highlight: The use of past modals allows for nuanced expression of probability and certainty in discussing past events.

Several examples illustrate the application of these structures:

• "The T-Rex must have been the most terrible dinosaur"
• "The T-Rex may have lived in hot climates"
• "The T-Rex can't have been good with its arms"

These sentences demonstrate how past modals can be used to speculate about historical or prehistoric events with varying degrees of certainty.