1. 5.8 More on Couldn’t Have
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2. couldn’t + base form
and
couldn’t have + base form
have different meanings:

3. couldn’t + base form means that it
didn’t happen because it wasn’t
possible:

4. Examples:
I couldn’t come to class last week
because I was sick.
He couldn’t find a job, so he decided to
go back to his country.
We couldn’t go swimming because
there was thunder and lightning.

5. couldn’t have + base form is used to
express disbelief in what someone
is saying:

6. Example:
My neighbor says that my dog bit
her, but it couldn’t have been my
dog because I never let mind
outside off-leash.

7. Example:
A: My parents voted for Kennedy in
1964.
B: What? They couldn’t have voted
for him in 1964. He died in 1963

8. Example:
A: I think I saw your brother at the
library yesterday.
B: It couldn’t have been him. He’s in
Europe on vacation.

9. Compare:
a. I couldn’t vote in the The speaker didn’t vote
last election because I was because he/she was out of
out of town. town.
b. You say you voted in the The speaker doesn’t
last election? You couldn’t believe that the other
have voted because you person said.
weren’t a citizen at the
time.

10. Compare:
a. I couldn’t move the The speaker didn’t move
refrigerator myself, so my the refrigerator alone. It
brother helped me. was impossible.
b. You say you moved the The speaker doesn’t
piano by yourself? You believe that the other
couldn’t have moved it by person said.
yourself. It’s too heavy for
one person.

11. Couldn’t have done something is
also used when showing gratitude
or appreciation for something, or
for someone’s help:

12. Example:
Thanks so much for helping me
paint my house. I couldn’t have
done it without you.

13. Example:
I couldn’t have found this place
without my GPS.