Exercicis de modals of deduction — Anglès 1r Batxillerat

'He might/could be in the library or at home.' Possibilitat sense certesa: might/could + infinitiu sense to (be).

'You must be exhausted.' Deducció positiva forta a partir de l'evidència (12 hores de feina): must + infinitiu sense to.

must love reading.
Tenim una prova clara (una col·lecció enorme), així que la deducció és gairebé segura. Must + infinitiu sense to.

can't be at school today.
Pel que sabem, és impossible que hi sigui: can't expressa una deducció negativa forta.

could (o might) be in the library.
No n'estem segurs, només és una possibilitat. Can't seria dir que és impossible.

They must be out.
Deduïm gairebé amb certesa a partir de les proves (llums apagats i ningú respon).

Fals.
En una deducció, can't be vol dir 'és impossible que sigui', no pas 'no té permís'. Pensa que és l'oposat de must be.

She must be very tired.
Després d'un verb modal fem servir l'infinitiu sense to.

The dog must have eaten it.
Per a deduccions fortes sobre el passat usem must have + participi (eat - ate - eaten).

must i can't (gairebé 100 %: must = segur que sí, can't = segur que no) → might i could (possibilitat, aprox. 50 %).
Might i could són pràcticament sinònims en les deduccions.

'She must pass the exam' (deducció positiva forta) o, segons el context, 'might pass'. La versió amb alta certesa és 'must pass'. Amb infinitiu sense to.

'That woman can't be Tom's mother; she's far too young.' Deducció negativa forta (impossible): can't + infinitiu sense to.

'She might/may/could have left it at home.' Possibilitat sobre el passat: might have + participi (left).

'It must have rained during the night.' Deducció positiva forta sobre el passat: must have + participi (rained).

'You should have called me when you arrived.' Falta el 'have': l'estructura és should have + participi (should have called).

The thief can't have used the front door.
És impossible que l'hagi fet servir, ho deduïm del fet que estava tancada per dins.

a) Pere must be at work.
b) She can't have forgotten.
Per al present, modal + infinitiu; per al passat, modal + have + participi.

Someone must be working late.
Si la deducció és sobre una acció en curs ara mateix, usem modal + be + verb en -ing.

a) She must have gone home. Després de have cal el participi (gone), no el past simple.
b) He can't have taken it. Després d'un modal, have (no has).

Model: He might have lent it to a friend. / Someone could have stolen it.
Might have i could have + participi expressen possibilitats sobre el passat sense estar-ne segurs.

They might (could) have gone on holiday, or they might (could) be in the garden.
Primera possibilitat sobre el passat (might have + participi) i segona sobre el present (might + infinitiu).

'He must have gone home; his coat isn't here.' La deducció sobre el passat és modal + have + participi (must have gone), no el passat simple.

'I shouldn't have told her the secret.' Penediment d'una acció feta: shouldn't have + participi (told).

'He should have checked the weather.' 'He should have taken a map.' 'He shouldn't have left his phone at home.'

Model: It must have been windy last night (fulles al pati). Someone must have left the window open. It might have rained inside, so the floor is wet.
Fixa't que cada deducció usa modal + have + participi perquè parlem del passat, i que must va amb més seguretat que might.

L'oposat de must per a una deducció és can't, no mustn't, que s'usa per prohibir (You mustn't smoke here).
Correcte: You can't be serious!

a) They might (could) have missed the bus.
b) He can't have lied.
c) She must have been crying. (Modal + have been + verb en -ing indica una acció que es perllonga en el passat.)

She might (could) be in the library, or she might (could) have gone home.
She can't have gone home.
Then she must be in the canteen.
Es combinen present (be) i passat (have gone) segons el moment de l'acció.

Might have: és una possibilitat (no estem segurs).
Must have: estem gairebé segurs que sí que ho va ser.
Can't have: estem gairebé segurs que no ho va ser.
Les tres frases parlen del passat (modal + have + participi).

Model: Júlia hasn't been to school all week. She must be ill, because she looked very pale last Friday. She might have caught the flu from her brother. She can't be on holiday, because her parents are working. She could be at the doctor's right now.
Revisa que el passat porti have + participi i que facis servir tant must com can't i might.

a) must have been talking: deducció quasi segura sobre una acció en curs en el passat.
b) might (o may / could) still have been sleeping: només és una possibilitat.
c) can't (o couldn't) have been waiting: és gairebé impossible que hagin estat esperant.
L'infinitiu continu del passat (have been + -ing) posa l'accent en l'activitat en curs, no en el resultat.

a) She must have arrived by now: deducció sobre el passat recent, must have + participi.
b) They can't know the answer: després del modal, infinitiu simple.
c) He might have forgotten his keys: cal have + participi, no had.
d) That couldn't be true: infinitiu sense to.
e) You must be joking!: és una deducció sobre el present, així que s'usa l'infinitiu continu.

Models de resposta (s'accepten sinònims):
a) She has definitely (o certainly / surely) forgotten.
b) There's no way he is serious. (o He is definitely not serious.)
c) It's possible that they missed the flight. (o Perhaps / Maybe they missed the flight.)
Must i can't expressen gairebé certesa; might expressa només possibilitat.

a) Might not: és possible que no el sàpiga, però també podria saber-lo; hi ha dubte.
b) Can't: és impossible que el sàpiga, per exemple perquè no té forma d'haver-lo après; és una conclusió gairebé segura.
Error típic: usar mustn't per a la deducció negativa; en deducció, el negatiu de must és can't.

a) Expectativa: el paquet probablement arribarà, segons el que se sap.
b) Consell: recomanació a algú.
c) Expectativa: és lògic que ja hi sigui, però no n'estem segurs.
d) Deducció: estic gairebé segur que està de broma.
Com a deducció, should / ought to indiquen una conclusió probable basada en el curs normal dels fets; must indica una conclusió basada en proves.

a) He must have missed the train. (També She.)
b) It can't have been him; he is in London. (També couldn't.)
c) They must be sleeping now.
d) They might not have known. (També may not o could not amb sentit de possibilitat.)

a) can't: l'he vista fa cinc minuts, és gairebé impossible que hagi anat lluny.
b) must: hi ha una raó forta per concloure que està molt disgustada.
c) might: no tinc cap prova; només és una possibilitat.
d) can't: la finestra estava tancada per dins, per tant és impossible.

Model de resposta:
The photograph must be very old, because the car looks like a model from the 1950s. The people are wearing formal clothes, so they must have been going to a special event. The man might be the owner of the house, since he is standing in front of the door. The children can't be older than ten. The photo could have been taken in summer, as nobody is wearing a coat. Someone must have kept it carefully, because it isn't damaged.
Claus de correcció: (1) almenys quatre modals diferents; (2) distinció entre presents i passats (must be / must have been); (3) coherència entre prova i grau de certesa.

1. had (past perfect passiu).
2. must (també s'accepten might i could).
3. must.
4. have (can't have been).
5. had (unless he had known).
6. may (també might; may well have been).
7. under (under investigation).
8. cannot (també s'accepten can't i couldn't).

1. disappearance (prefix dis- i sufix -ance a partir d'appear).
2. unlikely.
3. security.
4. detailed.
5. unusual.
6. inspector.
7. knowledge.
8. assumption.

a) can't have been.
b) might have lied.
c) must have been celebrating.
d) may not be.
e) couldn't have finished.

La correcta és c).
a) He must have been very tired: tired és un estat i no admet la forma contínua.
b) They can't have seen the sign: deducció negativa forta.
d) The thief can't have used the main door: en deducció negativa no s'usa mustn't.
e) He must have gone home early: cal el participi.
f) ...he can't (o couldn't) have forgotten...: si n'estic segur i mai no falta, la conclusió és que és impossible que ho hagi oblidat.

a) The burglar must have left through the window.
b) She can't (o couldn't) have seen us; she wasn't there.
c) They might (may / could) still be waiting for us at the station.
d) The files might (may / could) have been deleted by mistake. (Infinitiu perfecte passiu.)
e) He can't be working today; his office is dark.

Model de resposta:
It is often said that first impressions last, and we all draw conclusions about strangers within seconds. I would argue that this habit is natural, yet it frequently leads to unfair judgements.
On the one hand, quick deductions can be useful. If a man is wearing a uniform, he must be a police officer or a soldier, and if a woman is carrying a violin case, she is probably a musician. Such inferences help us find our way through daily life.
On the other hand, they can easily be mistaken. A well-dressed man might be unemployed, and a quiet student may have excellent ideas that nobody ever hears. Moreover, a person who arrives late for an interview can't necessarily be careless; the bus could have broken down. Treating guesses as facts is therefore dangerous.
A sensible approach is to treat first impressions as hypotheses, not conclusions. We should ask questions and gather evidence before deciding what someone must be like.
In conclusion, deductions based on appearance are useful only when they are held lightly, and we should be ready to revise them as soon as better information appears.
Claus de correcció: (1) postura clara i exemples; (2) modals de deducció ben formats (present i passat); (3) connectors i registre formal.

a) She might have won is a deduction: it is possible that she won. She could have won can mean the same, but it often means that she had the chance to win and did not.
b) They should have arrived expresses an expectation (it is logical that they have arrived, although I am not sure, or perhaps they were late). They must have arrived is a firm deduction based on evidence.
c) You may not enter is a prohibition (permission is refused). You may not be right is a deduction: it is possible that you are wrong.

1. may (també might; may well date back).
2. must.
3. must.
4. can't (també s'accepten cannot i couldn't).
5. may (també might o could).
6. no (there is no proof yet).
7. to (bound to change).
8. would (would not be surprised).

1. Scientists.
2. deduction.
3. conclusions.
4. reliable.
5. convincing.
6. revelation.
7. reasoning.
8. discussion.

a) might not have got (també gotten en anglès americà).
b) couldn't have been.
c) must be working.
d) may well have (també might well have).
e) could have escaped.

a) The film might (may / could) have already started.
b) He can't be Spanish with that accent.
c) She may well not have understood the question.
d) Someone must have been using my laptop.
e) They can't (o couldn't) have forgotten.

Model de resposta:
The Internet gives us instant access to images and videos from all over the world, but not everything that we see online is genuine. In my opinion, we should treat online content with caution.
First, technology has made manipulation easy. A photograph of a dramatic event may have been edited, and a viral video might have been filmed years ago in a completely different place. If a clip seems too good to be true, it probably is.
Second, some sources are clearly unreliable. A website that shows no author and no references can't be trusted, and a message that asks you to share it immediately must be designed to spread quickly rather than to inform.
Nevertheless, it would be wrong to distrust everything. Respected news organisations check their facts, and scientific journals publish studies that have been reviewed by experts. Learning to tell the difference is a key skill.
To conclude, we should neither believe everything nor reject everything. By checking sources and asking who might benefit from a story, we can draw sensible conclusions about what is probably true.
Claus de correcció: (1) postura clara amb arguments; (2) modals de deducció variats i ben usats; (3) cohesió i registre formal.