Auxiliary Verbs

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can

1. ability: he can lift 500N.
2. permission: you can go home now.
3. circumstantial possibility: even expert drivers can make mistakes | water can boil | the absence of legs cannot disguise their affinities with mammals | I can’t believe that we are faced with that sort of choice.
4. conjecture: she can’t be tired now.

may

1. permission.
2. conjecture.
3. circumstantial possibility.

must, have

1. duty: you must do military service.
2. necessity: I have to call my mom.
3. strong conjecture: He must be hungry.

should, ought

1. expectation based on common sense: it should be obvious that humans walk on two feet.
2. duty.

will

1. volition: I will lose weight.
2. cooperativeness: the door won’t open.
3. disposition: after sad things, happy things will happen.
4. definite conjecture: he will be a doctor | they had imagined that whatever or whoever it was that controlled their surroundings would do so.

would

1. a polite opinion or suggestion: I would be happy to help | would you like some help?
2. past habit: I would sometimes travel alone.

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