COULD (Auxiliary Verb)
Permission or Polite request
- - could is more polite expression than can
- could have the meaning of permission and request like can
(ex) Could you turn off the radio?
(ex) I feel thirsty. Could you give me a glass of water?
- - could is the past tense of can
(ex) He said " I can swim for two hours."
= He said that he could swim for two hours.
Possibility in the future or now
- - Sometimes could indicate possibility in the future or
- Sometimes could has a similar meaning to may and might
She is not in classroom. She could be sleeping in her room.
-> This sentence is just possibility.
(ex) "We are late." "Don't worry, we could arrive at bus gateway on
-> This sentence is possibility in the future.