Advanced Modal Verbs of Deduction and Speculation

Lesson 10: Advanced Modal Verbs (Deduction about the Past).

1. Overview
Make logical deductions and speculations about past events using modal verbs followed by "have + past participle".

2. Structures for Past Speculation
- Must have + V3 (Certainty about the past): He didn't reply to my messages; he must have fallen asleep.
- Might / May / Could have + V3 (Possibility in the past): The server is down; someone might have attacked it.
- Can't / Couldn't have + V3 (Impossibility in the past): He couldn't have written this bug-free code; he just started learning yesterday.

3. Practice Exercise
Complete the sentences with the correct modal structure (must have, might have, can't have):
1. The package arrived safely; the courier _____ (deliver) it this morning.
2. He missed the meeting completely; he _____ (forget) about the time.