MODALS OF DEDUCTION AND SPECULATION EXERCISE 1 (ESL)
level: Intermediate (B1/B2)
✓ Useful for Cambridge B2/C1
✓ Useful for IELTS
Modals of speculation are used to express how certain or uncertain we are about a present situation. Each modal reflects a different point on the certainty scale: must for near-certainty, might/could for possibility, and can't for near-impossibility. The grammar review below explains the full scale with examples.
Need a refresher? Jump to the grammar review ↓
Need a refresher? Jump to the grammar review ↓
Choose the correct modal — must, might, could, or can't — to express the speaker's degree of certainty.
GRAMMAR REVIEW! Modals of deduction and speculation
Modals of speculation are used to express how certain or uncertain we are about a present situation. The modal you choose reflects your degree of confidence — from near-certainty to near-impossibility.
Near-certain (positive): Use when the evidence strongly points to one conclusion.
She’s been working for 12 hours straight. → strong deduction about her state
Near-certain (negative): Use when something is logically impossible or highly unlikely.
He just ate an enormous meal. → strong negative deduction about hunger
Possible but uncertain: Use when something is a genuine possibility but not confirmed.
I’m not sure where she is. She ________ be at the gym.
The key is reading the evidence in the sentence carefully. The strength of the deduction — not the grammar alone — determines which modal fits.
Modals of speculation are used to express how certain or uncertain we are about a present situation. The modal you choose reflects your degree of confidence — from near-certainty to near-impossibility.
Near-certain (positive): Use when the evidence strongly points to one conclusion.
She’s been working for 12 hours straight. → strong deduction about her state
Near-certain (negative): Use when something is logically impossible or highly unlikely.
He just ate an enormous meal. → strong negative deduction about hunger
Possible but uncertain: Use when something is a genuine possibility but not confirmed.
I’m not sure where she is. She ________ be at the gym.
The key is reading the evidence in the sentence carefully. The strength of the deduction — not the grammar alone — determines which modal fits.
CHECK OUT OUR OTHER MODAL VERB EXERCISES:
Past modals 1 (must/might/could/should + have) (I)
Mixed modals 1 (can, should, must) (I)
Mixed modals 2 (can, should, must) (I)
Mixed modals 3 (can, should, must) (I)
To or not to? Modals vs. regular verbs 1 (B)
To or not to? Modals vs. regular verbs 2 (B)
Modals (couldn’t / might not) (I)
More grammar exercises
Past modals 1 (must/might/could/should + have) (I)
Mixed modals 1 (can, should, must) (I)
Mixed modals 2 (can, should, must) (I)
Mixed modals 3 (can, should, must) (I)
To or not to? Modals vs. regular verbs 1 (B)
To or not to? Modals vs. regular verbs 2 (B)
Modals (couldn’t / might not) (I)
More grammar exercises
