This document provides examples of modal verbs followed by infinitives or past participles in English and Spanish. It shows modal verbs like can, could, may, might, should, ought to, had better, must, and don't have to followed by infinitives or past participles to express possibilities, necessities, or suggestions in the past. Examples are given of conversations where the second speaker uses a modal verb with an infinitive or past participle to speculate about what happened based on evidence presented by the first speaker.

2. Modal + Infinitive Modal + have participle
CAN CAN
COULD COULD
MAY MAY
MIGHT MIGHT
SHOULD INFINIT. SHOULD HAVE PARTC.
OUGHT TO OUGHT TO
HAD BETTER HAD BETTER
MUST MUST
DON’T HAVE TO DON’T HAVE TO
ETC… ETC…

3. Before After
The water You shouldn’t
must be very have been in
cold cold water

4. A: He hasn’t got any
money
B: He may have lost it
Puede que haya perdido

5. A: He has spiky hair
B: He shouldn’t have plugged it
No debería haber enchufado

6. A: He was playing
baseball alone
B: He must have broken the window
debe haber roto

7. A: He has run over
the signal
B: He mustn’t have seen it
No debe haber visto

8. A: He has both arms
broken
B: He may have had an accident
puede que haya tenido

9. A: She hasn’t stopped
B: She had to have stopped
tenía que haber parado

10. A: His car is brand new
B: He doesn’t have to have washed it
No tenía por qué haber lavado

11. A: He has failed
the exam
B: He should have studied more
debería haber estudiado

12. A: She is really happy
B: She must have won the lottery
debe haber ganado

13. A: She is angry
B: He may have won her
Puede que haya ganado

14. A: He is crying
B: He must have lost his toy
Debe haber perdido

15. A: His car has
stopped. He has run
out of petrol
B: He could have filled the tank before
podía haber llenado