MODAL VERBS

• CAN : ability and permission in the present.
• COULD: ability and permission in the past.
• SHOULD: to give advice or opinion.
• MUST: to talk about a strong obligation.
• MUSTN'T: to say that something is prohibited.
• HAVE/ HAS TO: to talk about obligations.
• DON'T/DOESN'T HAVE TO: to talk about things that aren't necessary or obligatory.