This document provides guidance on using perfect modals in the passive voice to present theories about past events. It discusses identifying and using structures like "might have been," "could have been," "must have been," "had to have been," and "couldn't have been" to speculate about the past with varying degrees of certainty, from not certain to almost certain to very certain. An activity is included where learners analyze example sentences using these structures.

1. Good morning!

2. • 3
• How to use MEC
• Identify and use perfect modals in
passive voice to present a theory about a
past event.
• Practice skills to present a theory about a
past event.
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3. 3
1/14Activity: Grammar. Look at the sentences below and identify the use
and the structure.
Present a
theory about
a past event
Perfect modals to speculate about the past.
Not certain
OThe dinosours might have been killed by a meteor.
OThe trees could have been destroyed by a fire.
Almost certain
OThe stone balls must have been moved using
animals
Very certain
OThe crater had to have been caused by a
meteorite.
OThe trees couldn’t have been burned in a fire.

4. 3
1/14
Activity: Grammar. Look at the structure.
Present a
theory about
a past event
Perfect modals to speculate about the past.
modal verb have been
verb in
past part