Modals of Deduction (Past)

• Use past modals of deduction to make guesses about things that happened in the past based on evidence in the present.
• Modal
• Meaning
• Example
• must have + V3
• Almost certain it happened
• They must have checked prices in Chicago.
• might have / could have + V3
• Possible it happened
• We might have missed the client in Boston.
• can't have / couldn't have + V3
• Almost certain it didn't happen
• She couldn't have ignored our email in London.
• Remember
• Use must have for strong positive deductions about the past.
• Use can't have or couldn't have for things that were impossible in the past.
• Use might have or could have for possibilities in the past.
• Always use the third form of the verb (past participle) after the modal + have.
• Examples
• Mark must have called the manager in New York.
• Sarah can't have forgotten our meeting in Seattle.
• They might have lost the contract due to bad timing.
• Common mistakes
• They must missed the deadline in Chicago.
• They must have missed the deadline in Chicago.
• She can't has known about the price in Boston.
• She can't have known about the price in Boston.

Complete the sentences

• Kevin didn't reply to our email, so he (see) ____ it in Seattle.
• Our proposal was too expensive, so we (lose) ____ the deal in New York.
• The client loved our software features, so they (reject) ____ us in London.
• Rachel answered every question clearly, so she (be) ____ ready for the call in Boston.
• They bought from our rival in Chicago, so they (find) ____ a better discount.
• David was on holiday in Miami, so he (send) ____ the report from Seattle.

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