Verbs: patterns and past deductions

Verb patterns change meaning

A following to-infinitive or -ing form can change a verb’s meaning. Remember to do means not forgetting a task; remember doing means recalling a past experience.

Worked example: Remember to lock the door before you leave. This is a task still to be done.

Evidence and past deductions

Use modal + have + past participle for views about the past. Must have expresses a strong deduction; might have expresses a possibility, not a proven fact.

Worked example: The lights are off and their bags are gone. They must have left. This is a strong deduction from clues; the speaker could still be mistaken.

Separate explained answers

1. to confirm Remember to confirm refers to a task that needs to be done. Remember confirming would mean recalling the action.

2. I remember calling her. Remember calling refers to a memory of making the call. It does not itself prove that the memory is accurate.

3. They might have been busy. Might have been marks a possible past explanation. Do not turn uncertainty into an accusation.