can('t):có thể:You can't park here.
could(n't):có thể:She could sing very well.
had better(not):nên:Children had better go to bed early.
must(n't):nên:You must obey your parents.
ought (not) to:nên:You ought to go to the doctor.
should(n't):You shouldn't play with knife.
may:có thể:He may at school.
might:có thể:She might have been at school.
will:sẽ:He will visit his parents next week.
have/has to:phải:Students have to wear uniforms at school.
