e supposed to do sth: 表示已经计划好的,然后按照计划应该做的.You should make an appointment first and you are supposed to be arrive on time.
should do sth: 主管看法上的应该做什么事情.you should tight safe belt when you are driving.开车时应该系好安全带.
ought to与should意思接近,大多数情况下二者可以互换,但是should谈的是自己的主观看法,ought to则更多反映客观情况,在谈到法律、义务和规定时使用.