Student or Learner
According to the following attachments:
Why we use "have to " and "must" in the sentences.
I know we use "have to" to talk about external obligation and "must" for internal obligation. and both of them used for laws and rules.
But why did we use "have to " and "must"?!
Can we use "should"?! because we wanted to give suggestions or advice.
I feel that the speaker intended to add emphasis, stressing that the suggestions must/have to be accepted.
Not a teacher.