2. Choose the right form. Why the other
option is wrong?
1. A: That sounds like the neighbours’ dog.
B: It can’t be / mustn’t be. They’ve gone away for the weekened
and they’ve taken the dog with them.
2. There’s no sound coming from his room. He probably hasn’t /hasn’t
probably woken up yet.
3. A: Didn’t you hear that bang in the middle of the night? It woke me up.
B: Yes, I did. It must be / must have been the wind.
4. Can you turn the music down? If we make too much noise, the woman
upstairs will likely call / is likely to call the police.
5. A: Can I speak to Raymond, please?
B: Sorry, he’s not back yet. He must work / must be working late.
3. PRESENT DEDUCTION, SPECULATION &
EXPECTATION
POSITIVE CERTAINTY
MUST + inf
They must be in Bahamas now. I’ve just seen them scuba
diving on Instagram.
NEGATIVE CERTAINTY
CAN’T/ COULDN’T + inf
They can’t land in Bahamas. Flights are cancelled till
Wednesday due to a hurricane.
PROBABLE CERTAINTY
MAY/ MIGHT/ COULD + inf
MIGHTN’T/ MAY NOT + inf
They may not fly to Bahamas, as she is due in a month.
EXPECTATION
SHOULD/ OUGHT TO + inf
The couple should be home by Friday as their honeymoon lasts
one week. (They are expected to be back by Friday)
4. PAST DEDUCTION & SPECULATION
POSITIVE CERTAINTY
MUST HAVE + pp
The five-year-old boy must have taken his hamster
with him. Someone saw a rodent on the shelves.
NEGATIVE CERTAINTY
CAN’T/ COULDN’T HAVE + pp
The infant can’t have taken all the cereal boxes off
the shelves. His parents kept an eye on him at all
times.
PROBABLE CERTAINTY
MAY/ MIGHT/ COULD HAVE + pp
MIGHTN’T/ MAY NOT HAVE + pp
The boy might have panicked when he found a rat in
the cereal aisle.
REGRET / EXPECTANCY
SHOULD/ OUGHT TO HAVE + pp
I should have called you before you left. (regret)
His parents should have cleaned up the mess.
(Expectation: He expected his parents to have
cleaned up the mess)
5. OTHER EXPRESSIONS FOR
SPECULATION
• Be bound to + inf (inevitable)
He was found guilty of doping and is bound to lose his medal.
• Be likely/ unlikely to + inf (probable)
A new election is likely to be held early next month.
• Will definitely/ probably + verb
Justin will definitely turn down the offer.
• Definitely/probably won’t + verb
Claire probably won’t accept the job.
