It's wrong to approach people when they are busy.
Milton arrived at his professor's office on his way to his next class but his professor was talking to another student.
Milton needed to ask his professor a question.
Milton decided to come back after his class to ask the question.
Milton interrupted the professor and student stating he was in a rush before asking his question.
Milton's professor happily answered his question.
Milton's professor chastised him and told him to come back later.