Modals of Deduction (Past)

• When we want to guess about things that happened in the past, we use past modals of deduction. We choose the modal depending on how sure we feel about our guess.
• Modal
• Meaning
• Example
• must have + V3
• almost certain it happened
• They must have rejected our app yesterday.
• might have / could have + V3
• possible it happened
• We might have forgotten the demo account.
• can't have / couldn't have + V3
• almost certain it didn't happen
• They couldn't have checked the metadata.
• Remember
• Use 'must have' with a past participle when you are sure something was true in the past.
• Use 'might have' or 'could have' when you think it is possible, but you are not certain.
• Use 'can't have' or 'couldn't have' when you are sure something did not happen.
• Never use 'musted have' or 'might has'; the modal verb stays the same for all subjects.
• Examples
• Kyle must have submitted the wrong build to Apple in Austin.
• Megan might have overlooked a detail in the screenshots.
• They can't have tested the in-app purchase properly in London.
• Common mistakes
• They must missed the reviewer notes in Boston.
• They must have missed the reviewer notes in Boston.
• She can't has rejected our design in New York.
• She can't have rejected our design in New York.

Complete the sentences

• Brian (must / miss) ____ the app store guidelines in Seattle.
• Sarah (might / forget) ____ to attach the demo account in Chicago.
• They (can't / check) ____ the screenshots in San Francisco.
• Mark (must / send) ____ the wrong build to Apple in Austin.
• Emily (could / misinterpret) ____ the rejection notice in London.
• We (couldn't / delete) ____ the metadata file in New York.

Sources: photo by PNW Production on Pexels