to have to; to have a duty or a responsibility to

The children are supposed to be at school by 8.45 a.m. 孩子们应该在早上8：45之前到校。

What are you doing out of bed - you're supposed to be asleep. 你不睡觉起来干什么——你早该睡着了。

You're not supposed (= allowed) to park here. 你不能把车停在这儿。

to be intended to

These batteries are supposed to last for a year. 这些电池应该能用一年。

We were supposed to have gone away this week, but Debbie's ill so we couldn't go. 这周我们本该走了，但是戴比病了，所以我们走不了了。

How am I supposed to (= how can I) find that much money by the end of the week? 我怎么能在周末之前弄到那么多钱呢?

used to show that you do not believe that something or someone really is what many other people consider them to be

a supposed genius 所谓的天才

The costs of the programme outweigh its supposed benefits. 这个方案的成本超出了它可能会带来的收益。