Obligation (+Necessity&Prohibition)
Internal (Strong Personal/Moral Duty) must
External (Rules, Circumstances) have to
Practical (Practical fact) need to
Negatives:
Obligation to not do / prohibition mustn't
No Obligation / optional don't have to
No Obligation / optional (needn't*) don't need to
*forma vieja; needn't have - no tenías que hacer algo que has hecho*
Moral/formal/logical advice ought to
Milder advice/recommendation should
Obligation as advice
Strong/urgent must
Inevitable from circumstances have to
Subjective practical necessity need to
Moral/formal/logical advice to not do ought not to
Milder advice/recommendation shouldn't
Obligation as advice
Strong/urgent/ -> Prohibition mustn't
(removes obligation don't have to)
(removes necessity -> reassurance don't need to)
Very certain (that it is) must
Very probable should
Probable (logical, formal) ought to
Negatives:
Very certain (that it is NOT) can't
Very probable shouldn't
Probable (logical, formal) ought not to
Moderately certain (a bit formal) may
Low certainty might
Low certainty, in a hypothetical/conditional could
Capacity: inn general, the possibility exists can
Negatives:
Moderately certain (formal) may not
Low certainty might not
Low certainty in a hypothetical/conditional couldn't
Ability can
Ability: past, hypothetical/conditional could
Permission(formal) may
Permission(informal or spoken) can
Permission(polite, formal & informal) could
Negative:
Statements = lack (falta) of permission or ability
BUT negative questions with *permission* are for...
...requesting to not do something: "May/Can/Could I not go?"
...showing a surprised/objecting request: "Can't I go?"
...trying to be more polite/persuasive: "Couldn't I go?"
I don't care if you don't want to go to school, you ________.
A) must
B) have to
C) need to
D) needn't have
Correct answer: B) have to (external obligation -> it's the rule/law)
You ________ probably try to sleep after work--you seem very exhausted.
A) ought to
b) should
c) must
d) need to/have to
b) should (mild recommendation)
The students look sad. They _______ have received terrible marks.
A) must
B) should
C) ought to
A) must - very certain
It _____ rain tomorrow. There are 50/50 odds.
A) may
B) might
C) could
D) can
A) may - moderate possibilities
____ I go to the bathroom?
A) may
B) can
C) could
A) may - formal permission
B) can - informal permission
C) could - formal permission
If you want to be a good person, you __________ hurt other people.
A) mustn't
B) don't have to
C) don't need to
Correct answer: A) musn't (Prohibition)
According to government research, people ________ save three to six months of their income a year.
A) ought to
b) should
c) must
d) need to/have to
a) ought to (official/formal recommendation, logical)
The package ________ be arriving tomorrow. The email said it would (be arriving tomorrow).
A) must
B) should
C) ought to
B) should - very probable
"Does it snow in Madrid?"
"It _____ snow around January, but it almost never happens."
A) may
B) might
C) could
D) can
D) can - in general it is possible
When I was a kid, I ______ swim faster than the other kids.
A) may
B) can
C) could
C) could - past ability
I'm so tired. I _______ sleep.
A) must
B) have to
C) need to
C) need to (practical necessity/fact of life)
You ________ see that movie! It was a life-changing experience.
A) ought to
b) should
c) must
d) need to/have to
c) must (very strong recommendation)
That _______ be his car--it's too dirty and he is a clean freak.
Must, should, ought to, can't, shouldn't, or ought not to?
can't - certainty that it is NOT
I finally got a good mark. I _______ fail after all.
A) may not
B) might not
C) couldn't
D) can't
A) may not, or B) might not
(Might: more common in conversation)
(May: can be used for a bit more certainty)
What!? ________ I go too?
A) may not
B) can't
C) couldn't
B) Can't - surprised request
A) You must pay your taxes.
B) You have to pay your taxes.
C) You need to pay your taxes.
What does each mean?
A) You must = strong personal/moral reasons
B) You have to = because of the rules/external pressure
C) You need = it's a fact of life necessity
A) You ought to call your mom.
B) You should to call your mom.
C) You must call your mom.
D) You have to call your mom.
E) You need to call your mom.
A) ought to - polite/formal/logical recommendation
B) should - normal/mild recommendation
C) must - strong recommendation (almost a requirement)
D) have to - recommendation from inevitability
E) need to - recommendation from subjective necessity
A) He must be arriving soon. He can't be far.
B) He should be arriving soon. He shouldn't be far.
C) He ought to be arriving soon. He ought not to be far.
What's the difference?
A) must / can't - very certain
B) should(n't) - a bit certain
C) ought (not) to - a bit certain / logical expectation
A) The train may arrive on time today.
B) The train might arrive on time today.
C) The train could arrive on time today.
D) The train can arrive on time today.
A) may - probable, 50/50
B) might - a bit probable - less than 50%
C) could - not probable/hypothetical/with specific conditions
D) can - wrong/unnatural -> can refer to a general capacity, but NOT a specific situation
A) He may walk to the park.
B) He can walk to the park.
C) He could walk to the park.
A) permission
C) permission or ability
C) past/conditional ability - ambiguous