① 表示“應該,推測,預定”,與be expected相近。
He is supposed to arrive at eight. I wonder why he is late. 他應該8點鐘到的,不知道為什么遲到了。
When the bell rings,the students are supposed to hand in their test papers. 鈴一響,學生們就該交考卷了。
② 表示“必須,有義務做”,與ought to相近。
Soldiers are supposed to keep military discipline. 軍人必須遵守軍紀。
We are not supposed to solve all of these problems. 我們沒有義務解決所有這些問題。