can/could能力 He can sing songs in French
He could swim at the age of 3
表示请求Can you help me carry the box into the room
Could you help me, please
可能性,表示有时会Jeff is clever, but sometimes he is very dull
针对不同时间表示推测(只能用于否定句和问句)can’t doHe can’t be at home right now, for I saw him go out just now
can't be doingHe can't be studying in the classroom, for I saw him go to the football field with a football
can’t have doneHe can’t have finished homework so soon, for he didn't come to school yesterday
Where can I have put my keys
may/might允许May I smoke here
表示祝福May you a happy life
针对不同时间表示推测(只能用于否定句和问句)may do He may come, but he is not sure
may be doingJim may be reading in the library
may have doneHe may have left the bag in the library
must肯定形式表示必须,应该;否定形式表示绝对禁止,语气强烈