Past Modal Continuous: Speculating About Ongoing Past Actions (B2 Grammar)

Past modal continuous is used to speculate about actions that were in progress at a past moment. Unlike past modals for completed actions (must have done, might have done), this structure focuses on what was happening at a specific time.

Quick tip: Use past modal continuous when you're speculating about WHAT WAS HAPPENING at a specific time. Use simple past modals when speculating about WHETHER SOMETHING HAPPENED (completed).

Past Modal Continuous (modal + have been + -ing)

Use past modal continuous to speculate about an action in progress at a past moment, not just a completed event. The structure is: modal + have been + -ing.

• She looks exhausted. She must have been working all night. (ongoing action)
• I called at 10 PM but no answer. They might have been sleeping. (in progress at that moment)
• His clothes were muddy. He could have been playing football. (activity in progress)
• The lights were on until midnight. Someone must have been studying. (continuous over time)

Continuous vs Simple: When to Choose Each

Choose continuous when you want to emphasize duration or an action in progress. Choose simple (must have done) when focusing on a completed result.

• He must have been driving for hours—he looked so tired. (emphasizes duration)
• He must have driven here from the coast. (completed journey)
• She might have been crying—her eyes were red. (ongoing state)
• She might have cried at the sad movie. (completed action)

Negative Forms (can't/couldn't have been + -ing)

Use can't/couldn't have been + -ing for impossible ongoing actions based on evidence. Use might not have been + -ing for uncertain negatives about ongoing actions.

• He can't have been sleeping—I heard him typing. (impossible based on evidence)
• She couldn't have been listening—she asked me to repeat everything. (clearly not paying attention)
• They might not have been paying attention during the announcement. (uncertain)
• He may not have been feeling well yesterday. (possible but not certain)

Common mistakes

• Not "She must have been work all night." — say "She must have been working all night.". Past modal continuous needs the -ing form: have been + working, not 'have been work'..
• Not "He might been sleeping when I called." — say "He might have been sleeping when I called.". Don't forget 'have'! The full structure is: modal + have + been + -ing..
• Not "They can't been listening carefully." — say "They can't have been listening carefully.". Negative forms also need 'have': can't have been + -ing..

Practise it

Look for time markers like 'at that moment', 'all night', 'for hours', 'when I called'—these signal ongoing actions that need past modal continuous.