Air Ticket

SUMMARY
Auxiliary	Present/Past Infinitive	Notion
he must	use a computer	obligation (by someone)
he has to	‘’	obligation (circumstances)
he had to	‘’	past + obligation
he needs to	‘’	obligation
he doesn't have to	‘’	lack of obligation
he didn't have to	‘’	past + lack of obligation
he needn't	‘’	lack of obligation
he musn't	‘’	prohibition, ban
he should	‘’	advice
he ought to	‘’	advice
he may	‘’	permission / hypothesis
he may not	‘’	prohibition, ban
he might	‘’	suggestion
he could	‘’	suggestion
he can	‘’	ability
he will	‘’	future
he will have to	‘’	future + obligation
he won't have to	‘’	future + lack of obligation
he may have to	‘’	hypothesis + obligation
he may not have to	‘’	hypothesis + lack of obligation
he would	‘’	conditional
he would have to	‘’	conditional + obligation
he wouldn't have to use	‘’	conditional + lack of obligation
he must	have used a computer	past + probability
he should	‘’	past + advice
he ought to	‘’	past + advice
he needn't	‘’	past lack of obligation
he may	‘’	past + hypothesis
he may not	‘’	past + negative probability
he might	‘’	past + hypothesis
he could	‘’	past + hypothesis
he will	‘’	future in the past
he would	‘’	past + conditional