1、表示“假定的，被认为的”：例如，“He was supposed to arrive at noon, but he's still not here.”（他原本应该在中午到达，但他还没有到。）
2、表示“本应该，应当”：例如，“I'm supposed to go to the store, but I don't feel like it.”（我本应该去商店，但我没有心情去。）
3、表示“所谓的，据说的”：例如，“She's supposed to be the best singer in the world.”（据说她是世界上最好的歌手。）
4、表示“不太可能的”：例如，“It's supposed to rain tomorrow, but I don't think it will.”（明天应该会下雨，但我不认为会下。）
