Modal Auxiliaries
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Modal Auxiliary
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Function
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Differences
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Examples
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Can
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Ability
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· Generaly used in present
tense
· Indicate stronger posibility
· Not as formal as could in request
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He can climb a tall tree
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Informal permissions
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She can use my bike tonight
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Informal polite request
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Can i use your telephone?
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Impossibility (negative sentence) accurate 99 %
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He’s just had lunch. He can’t
be hungry
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Could
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Past ability
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· The past form of can
· Indicate a weaker possibility
· More formal than can when used in request
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He could swim fast when he was at 10 (past)
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Polite request
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Could i use your phone?
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Suggestion
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I need help in english?
You could talk to your teacher
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Possibility, accurate <50%
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Where is Clara?
She could be at the kitchen.
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Impossibility (negative sentence) accurate 99%
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He just had lunch. He couldn’t be hungry
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Be able to
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Ability
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· Express ability
· Possible in all tenses
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I’m able to help you.
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Must
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Strong necessity
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· Expresses obligation imposed by the speaker
· The speaker thinks it is necessary
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You must read that book now
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Prohibition (negative sentence)
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They must not open the door
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Centrainty, accurate 95%
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Clasra isn;t in her room. She must hang out at the mall
(present only)
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Have to
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Necessity
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· Express external obligations
· Someone else thinks it is necessary
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You have to read that book now
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Lack of necessity (not necessary)
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Tomorrow is holiday. We don’t have to go to class.
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Shall
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Polite permission to suggetion
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· Generaly used in present
tense
· Used more in formal than should
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Shall we begin the class?
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Future action (subject I & We)
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I shall call you later
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Should
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Advisablility
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· The past form of shall
· More formal than shall
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You should study harder tonight
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Centrainty, accurate 90%
(expetation)
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Ali should do well on the test (future only)
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Ought to
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Advisability
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· Sounds more formal than should
· Used less frequently
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You ought to study harder tonight
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Centrainty, accurate 90%
(expetation)
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Ali ought to have done well on the test (Past)
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Will
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Centrainty, accurate 100%
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· used to indicate future
· used in the formation of conditional clause type 1
· less polite than would
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She will come at 7 a.m (future only)
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Willingness
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The phone is ringing. I’ll get it.
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Polite request
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Will you please pass the paper?
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Would
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Polite request
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· used to indicate the past
· used in the formation of conditional clause type 2 and 3
· more polite and formal than
will
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Would you please pass the paper?
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preference
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I would rather call you than come over
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Repeated action in the past
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When i was child, i would go around to my grandparents
every weekend (past)
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Polite for ‘want’
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I would like to take a
rest for a short while
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Unfulfilled wish
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I would have watched TV, but it was broken
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Be going to
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Centrainty, accurate100%
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· used to for action with plan/thought
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She is going to come at 7 a.m
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Fixed plan
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I’m going to paint my fence
(future only)
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