You are supposed to do = You should do
be supposed to 相當(dāng)于一個(gè)情態(tài)動(dòng)詞,過(guò)去式要變形,現(xiàn)在時(shí)和將來(lái)時(shí)用原形舉一個(gè)例子好么，謝謝You are supposed to finish the job within the time limit.你應(yīng)該在時(shí)間限期內(nèi)完成工作（指現(xiàn)在也可，將來(lái)也可，因此現(xiàn)在沒(méi)有完成工作呢）You are supposed not to make the same mistakes again in future.今后你應(yīng)該不要再犯同樣的錯(cuò)誤（將來(lái)）I was supposed to go with them, but I was ill.我本來(lái)應(yīng)該和他們一起去的，但我病了（結(jié)果沒(méi)有去）