I share with you the complete list of phrasal verbs I used during 10 days in a row. Now it's your turn to use the same strategy and learn phrasal verbs too Ask your partner what each phrasal verb means.
All modal verbs are auxiliary verbs, which means they can only be used with a main verb. Modal verbs cannot be a main verb. They are used to express ideas such as possibility, prediction, speculation, deduction and necessity.
The correct usage of CAN and COULD in American Casual, Spoken English using "Modal Verbs", general rules to go by (never hard and fast or forever, always, aka: always exceptions but here's a really good start)